U.S. patent application number 15/622015 was filed with the patent office on 2018-12-13 for devices, methods, and systems for thermal management.
This patent application is currently assigned to MICROSOFT TECHNOLOGY LICENSING, LLC. The applicant listed for this patent is MICROSOFT TECHNOLOGY LICENSING, LLC. Invention is credited to Erin Elizabeth HURBI, Michael NIKKHOO.
Application Number | 20180356156 15/622015 |
Document ID | / |
Family ID | 64563920 |
Filed Date | 2018-12-13 |
United States Patent
Application |
20180356156 |
Kind Code |
A1 |
HURBI; Erin Elizabeth ; et
al. |
December 13, 2018 |
DEVICES, METHODS, AND SYSTEMS FOR THERMAL MANAGEMENT
Abstract
A heat transfer device, and methods and systems using such
devices, including a major surface wall forming a bottom side of
the device; a first hermetic chamber of a first design and with the
surface wall forming a bottom wall of the first vapor chamber; a
second hermetic chamber of a second design, positioned adjacent to
the first chamber along a length of the first surface wall, and
with the surface wall forming a bottom wall of the second vapor
chamber. The first chamber includes a first heat transfer medium
and a first wick arranged to transport the first heat transfer
medium to an evaporator region of the first chamber. The second
chamber includes a second heat transfer medium and a second wick
arranged to transport the second heat transfer medium to an
evaporator region of the second chamber.
Inventors: |
HURBI; Erin Elizabeth; (San
Francisco, CA) ; NIKKHOO; Michael; (Saratoga,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MICROSOFT TECHNOLOGY LICENSING, LLC |
Redmond |
WA |
US |
|
|
Assignee: |
MICROSOFT TECHNOLOGY LICENSING,
LLC
Redmond
WA
|
Family ID: |
64563920 |
Appl. No.: |
15/622015 |
Filed: |
June 13, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 2015/0216 20130101;
F28C 3/04 20130101; F28F 13/182 20130101; F28F 23/02 20130101; F28D
15/0233 20130101; F28D 15/04 20130101; F28C 3/02 20130101; F28C
3/08 20130101; H01L 23/427 20130101; H05K 7/20336 20130101; F28C
3/12 20130101; F28D 15/0266 20130101 |
International
Class: |
F28C 3/08 20060101
F28C003/08; F28F 13/18 20060101 F28F013/18; F28F 23/02 20060101
F28F023/02 |
Claims
1. A heat transfer device comprising: a substantially continuous
first surface wall forming a bottom side of the heat transfer
device; a hermetic first chamber of a first design, wherein the
first surface wall provides a bottom wall of the first chamber; a
hermetic second chamber of a second design different from the first
design, positioned adjacent to the first chamber along a length of
the first surface wall, wherein the first surface wall provides a
bottom wall of the second chamber; a first heat transfer medium
disposed in the first chamber; a first wick disposed in the first
chamber and arranged to transport a liquid phase of the first heat
transfer medium by capillary forces to an evaporator region of the
first chamber; a second heat transfer medium disposed in the second
chamber; and a second wick disposed in the second chamber and
arranged to transport a liquid phase of the second heat transfer
medium by capillary forces to an evaporator region of the second
chamber.
2. The heat transfer device of claim 1, wherein a total internal
volume of the first chamber is substantially greater than a total
internal volume of the second chamber.
3. The heat transfer device of claim 1, wherein the first wick
includes a wick portion disposed on a continuous second wall of the
heat transfer device; the second wick includes a wick portion
disposed on the second wall; the wick portion of the first wick and
the wick portion of the second wick portion have substantially
different average wick thicknesses, substantially different average
pore sizes, or comprise different wick materials.
4. The heat transfer device of claim 1, wherein a total mass of the
first heat transfer medium disposed in the first chamber is
substantially greater than a total mass of the second heat transfer
medium disposed in the second chamber.
5. The heat transfer device of claim 1, wherein when the heat
transfer device is operating in a thermal steady-state in which a
first heat load is being supplied to the evaporator region of the
first chamber and a second heat load, substantially equal to the
first heat load, is being supplied to the evaporator region of the
second chamber, a vapor temperature of the first heat transfer
medium around the evaporator region of the first chamber is
substantially greater than a vapor temperature of the second heat
transfer medium around the evaporator region of the second
chamber.
6. The heat transfer device of claim 1, wherein when the first
chamber is operating in a thermal steady-state at a first
steady-state vapor temperature, a heat transfer rate via the first
heat transfer medium is substantially greater than a heat transfer
rate via the second transfer medium when the second chamber is
operating in a thermal steady-state at the first vapor
temperature.
7. The heat transfer device of claim 1, further comprising: a first
side wall portion of the first chamber, wherein the first side wall
portion is directly attached to the first surface wall; a second
side wall portion of the second chamber, wherein the second side
wall portion is directly attached to the first surface wall and
adjacent to the first side wall portion of the first chamber; and a
vacuum or a thermally insulating material disposed between the
first side wall portion and the second side wall portion.
8. The heat transfer device of claim 1, further comprising: a first
heat rejection structure thermally coupled to the first chamber via
a first amount of surface area of an exterior surface of the first
chamber and arranged to receive at least 50% of latent heat
released by condensation of the first heat transfer medium; and a
second heat rejection structure thermally coupled to the second
chamber via a second amount of surface area of an exterior surface
of the second chamber and arranged to receive at least 50% of
latent heat released by condensation of the second heat transfer
medium, wherein the first amount of surface area is substantially
greater than the second amount of surface area.
9. An electronic assembly comprising: the heat transfer device of
claim 1; a first electronic component that generates heat during
operation of the electronic assembly, is thermally coupled to the
first chamber of the heat transfer device, and is arranged to
vaporize the first heat transfer medium included in the heat
transfer device at the evaporator region of the first chamber
during operation of the electronic assembly; and a second
electronic component that generates heat during operation of the
electronic assembly, is thermally coupled to the second chamber of
the heat transfer device, and is arranged to vaporize the second
heat transfer medium included in the heat transfer device at the
evaporator region of the second chamber during operation of the
electronic assembly.
10. The electronic assembly of claim 9, wherein a total internal
volume of the first chamber is substantially greater than a total
internal volume of the second chamber.
11. The electronic assembly of claim 9, wherein the electronic
assembly is arranged such that, when a temperature of the first
electronic component has increased to a first steady-state
temperature and a temperature of the second electronic component
has increased to a second steady-state temperature while the
electronic assembly is operating in a power on state, a vapor
temperature of the first heat transfer medium around the evaporator
region of the first chamber is substantially greater than a vapor
temperature of the second heat transfer medium around the
evaporator region of the second chamber.
12. The electronic assembly of claim 9, wherein the electronic
assembly is arranged such that, when the electronic assembly is at
a nominal powered on thermal steady-state, a first steady-state
temperature of the first electronic component is substantially
greater than a second steady-state temperature of the second
electronic component.
13. The electronic assembly of claim 9, further comprising: a first
heat rejection device thermally coupled to the first chamber via a
first amount of surface area of an exterior surface of the first
chamber and arranged to receive more than 50% of latent heat
released by condensation of the first heat transfer medium during
operation of the electronic assembly; and a second heat rejection
device thermally coupled to the second chamber via a second amount
of surface area of an exterior surface of the second chamber and
arranged to receive at least 50% of latent heat released by
condensation of the second heat transfer medium during operation of
the electronic assembly, wherein the first amount of surface area
is substantially greater than the second amount of surface
area.
14. The electronic assembly of claim 9, further comprising: a first
heat rejection device thermally coupled to the first chamber,
including a user-exposed surface, and arranged to receive at least
50% of latent heat released by condensation of the first heat
transfer medium during operation of the electronic assembly; and a
second heat rejection device thermally coupled to the second
chamber and arranged to receive at least 50% of latent heat
released by condensation of the second heat transfer medium during
operation of the electronic assembly, wherein the electronic
assembly is arranged such that, when the electronic assembly is at
a nominal powered on thermal steady-state, the user-exposed surface
of the first heat rejection device is at or below 40.degree. C.,
and a temperature of the second heat rejection structure is at or
above 50.degree. C.
15. The electronic assembly of claim 9, further comprising: a
passive heat rejection structure thermally coupled to the first
chamber; and an active heat rejection structure thermally coupled
to the second chamber.
16. The electronic assembly of claim 9, further comprising a heat
sink thermally coupled to the first chamber and the second chamber
via the first surface wall of the heat transfer device, arranged to
receive at least 50% of latent heat released by condensation of the
first heat transfer medium, and arranged to receive at least 50% of
latent heat released by condensation of the second heat transfer
medium.
17. The electronic assembly of claim 9, wherein the electronic
assembly comprises a head-mounted display device including the
first chamber, the second chamber, the first surface wall of the
heat transfer device, the first electronic component, and the
second electronic component.
18. The electronic assembly of claim 9, wherein: the first
electronic component is a first die portion of a die; and the
second electronic component is a second die portion of the die.
19. The electronic assembly of claim 9, wherein: the first
electronic component is a first die included in a multi-die chip
carrier; and the second electronic component is a second die
included in the multi-die chip carrier.
20. A method of cooling components in an electronic device, the
method comprising: including a heat transfer device according to
claim 1; thermally coupling a first electronic component that
generates heat during operation of the electronic assembly to the
first chamber of the heat transfer device; vaporizing a portion of
the first heat transfer medium included in the heat transfer device
by transferring heat from the first electronic component to the
evaporator region of the first chamber; thermally coupling a second
electronic component that generates heat during operation of the
electronic assembly to the second chamber of the heat transfer
device; vaporizing a portion of the second heat transfer medium by
transferring heat included in the heat transfer device from the
second electronic component to the evaporator region of the second
chamber.
Description
BACKGROUND
[0001] Electronic devices and systems include various electronic
components that generate heat during operation, such as, but not
limited to, logic processors, graphics processors, signal
processing units, batteries, power supplies, display devices, light
emitting components, electromechanical components, sensors,
amplifiers, digital to analog converters (DACs), analog to digital
converters (DACs), radio frequency (RF) transmitters, RF receivers,
and system on a chip (SoC) components. It is advantageous to
maintain electronic components at lower temperatures, as operating
temperature is a significant factor in determining reliability and
failure rates. Also, hotter components may degrade over their
lifespan, and additional power may be required to compensate for
the degradation, which in turn can result in additional
charge/discharge cycles for a battery supplying such power.
Further, higher temperatures can reduce efficiency or performance;
for example, some components may exhibit leakage power dependent on
component temperature. Other components may be similarly affected
if heat generated by a component is not effectively removed or
managed.
[0002] Decreases in component and device sizes have increased
challenges for thermal management. Miniaturization of electronic
components has led to increases in heat flux, with some
microprocessors reaching 200 W/cm.sup.2. Also, decreases in form
factor sizes for electronic devices have led to increasing compact
and/or stacked arrangements that increase densities of heat
generating components and restrict avenues for heat rejection.
Further challenges and constraints are imposed on mobile and
wearable electronic devices, as air blowers are often undesirable
or impractical in such devices, surfaces that come into contact
with users need to be maintained at safe or comfortable
temperatures, and surfaces with low thermal resistances, such as a
metal exterior surface, can still end up conducting too much heat
energy to a user's body even at lower temperatures.
[0003] Various techniques have been employed for removing heat from
electronic devices, including, for example, heat spreaders, heat
pipes, and finned heat sinks, sometimes in combination with air
flow from a passive vent or assisted by air blowers. Heat pipes and
vapor chambers offer very high thermal conductivities, but their
use in portable electronic devices has generally been limited to
high heat flux components such as microprocessors and graphics
processing units (GPUs). There remain significant areas for new and
improved ideas for applying heat pipes and vapor chambers in
portable electronic devices, and such improvements are also of
benefit for other uses of heat pipes and vapor chambers.
SUMMARY
[0004] A heat transfer device for thermal management and an
electronic assembly including the heat transfer device. The device
includes a substantially continuous surface wall providing a bottom
side of the device; a hermetic first chamber of a first design,
with the surface wall providing a bottom wall of the first vapor
chamber; and a hermetic second chamber of a second design different
from the first design, positioned adjacent to the first chamber
along a length of the surface wall, with the surface wall providing
a bottom wall of the second vapor chamber. A first heat transfer
medium is disposed in the first chamber, and a first wick is
disposed in the first chamber and arranged to transport a liquid
phase of the first heat transfer medium by capillary forces to an
evaporator region of the first chamber. A second heat transfer
medium is disposed in the second chamber, and a second wick is
disposed in the second chamber and arranged to transport a liquid
phase of the second heat transfer medium by capillary forces to an
evaporator region of the second chamber.
[0005] The electronic assembly includes a substantially continuous
surface wall; a first hermetic chamber of a first design, with the
surface wall providing a bottom wall of the first vapor chamber; a
second hermetic chamber of a second design different from the first
design, positioned adjacent to the first chamber along a length of
the surface wall, with the surface wall providing a bottom wall of
the second vapor chamber. A first heat transfer medium is disposed
in the first chamber, and a first wick disposed in the first
chamber and arranged to transport a liquid phase of the first heat
transfer medium by capillary forces to a an evaporator region of
the first chamber. A second heat transfer medium is disposed in the
second chamber, and a second wick disposed in the second chamber
and arranged to transport a liquid phase of the second heat
transfer medium by capillary forces to an evaporator region of the
second chamber. The electronic assembly may include a first
electronic component that generates heat during operation of the
electronic assembly, is thermally coupled to the first chamber, and
is arranged to vaporize the first heat transfer medium at the
evaporator region of the first chamber during operation of the
electronic assembly. The electronic assembly may include a second
electronic component that generates heat during operation of the
electronic assembly, is thermally coupled to the second chamber,
and is arranged to vaporize the second heat transfer medium at the
evaporator region of the first chamber during operation of the
electronic assembly.
[0006] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used to limit the scope of the claimed
subject matter. Furthermore, the claimed subject matter is not
limited to implementations that solve any or all disadvantages
noted in any part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The drawing figures depict one or more implementations in
accord with the present teachings, by way of example only, not by
way of limitation. In the figures, like reference numerals refer to
the same or similar elements.
[0008] FIG. 1A illustrates an external top isometric view of a
fully assembled example heat transfer device embodying aspects of
techniques described herein. FIG. 1B illustrates an exploded bottom
isometric view of the heat transfer device illustrated in FIG. 1A.
FIG. 1C illustrates another exploded bottom isometric view of the
heat transfer device illustrated in FIGS. 1A and 1B, with only a
bottom wall removed from the remaining walls.
[0009] FIG. 2A illustrates a cross-section view, corresponding to
the cross-section labeled "2A" in FIG. 1A, of the heat transfer
device illustrated in FIGS. 1A, 1B, and 1C. FIG. 2B illustrates an
example graph of temperatures over time for the two thermal domains
provided by the heat transfer device illustrated in FIG. 2A and a
single thermal domain provided by a conventional single-chambered
vapor chamber. FIG. 2C illustrates an alternative embodiment in
which a liquid phase of a heat transfer material may flow between
two hermetic chambers included in the heat transfer device
illustrated in FIG. 2A. FIG. 2D illustrates a cross-section view,
corresponding to the cross-section labeled "2D" in FIG. 1A, of the
heat transfer device illustrated in FIGS. 1A, 1B, 1C, and 2A. FIG.
2E illustrates a cross-section view, corresponding to the
cross-section labeled "2E" in FIG. 1A, of the heat transfer device
illustrated in FIGS. 1A, 1B, 1C, 2A, and 2D.
[0010] FIG. 3 shows a heat transfer device illustrating examples of
features that may be selectively included in the heat transfer
devices described herein.
[0011] FIG. 4 shows a heat transfer device illustrating examples of
additional features that may be selectively included in the heat
transfer devices described herein.
[0012] FIG. 5A illustrates an example of a substrate with
electronic components mounted thereon and/or therein that are
associated with two different thermal domains. FIG. 5B illustrates
an example of a heat transfer device that is adapted to provide
first and second thermal domains for the electronic components
shown in FIG. 5A. FIG. 5C illustrates an example electronic
assembly with the substrate and electronic components illustrated
in FIG. 5A coupled to the heat transfer device illustrated in FIG.
5B.
[0013] FIG. 6A illustrates an example heat transfer device with a
vacuum or thermally insulating material disposed between two
adjacent chambers. FIG. 6B illustrates an example heat transfer
device with a gap between two adjacent chambers.
[0014] FIG. 7A illustrates an example heat transfer device with a
vacuum or thermally insulating material disposed between two
adjacent chambers. FIG. 7B illustrates an example heat transfer
device with a gap between two adjacent chambers.
[0015] FIG. 8A illustrates an example of a multi-die package that
may be thermally coupled to a heat transfer device to provide
separate thermal domains for dice included in the multi-die
package. FIG. 8B illustrates an example cross-section (labeled "8B"
in FIG. 8A) of the multi-die package illustrated in FIG. 8A and an
example heat transfer device thermally coupled to, and providing
separate thermal domains for, a first die and a second die included
in the multi-die package. FIG. 8C illustrates an example
cross-section (labeled "8C" in FIG. 8A) of the multi-die package
illustrated in FIG. 8A and an example heat transfer device
thermally coupled to, and providing separate thermal domains for, a
die and a three-dimensional dice stack included in the multi-die
package.
[0016] FIG. 9A illustrates an example of a die that may be
thermally coupled to a heat transfer device to provide separate
thermal domains for portions of a single die. FIG. 9B illustrates
an example cross-section (labeled "9B" in FIG. 9A) of the die
illustrated in FIG. 9A and an example heat transfer device
thermally coupled to, and providing separate thermal domains for, a
first die portion and a second die portion included in the die.
[0017] FIG. 10 illustrates an example of a portable electronic
device incorporating a heat transfer device as discussed in
previous examples.
[0018] FIG. 11A illustrates an example heat transfer device
arranged to provide multiple thermal domains for the portable
electronic device illustrated in FIG. 10. FIG. 11B illustrates an
example in which the heat transfer device illustrated in FIG. 11A
is included in the portable electronic device illustrated in FIG.
10.
DETAILED DESCRIPTION
[0019] In the following detailed description, numerous specific
details are set forth by way of examples in order to provide a
thorough understanding of the relevant teachings. However, it
should be apparent that the present teachings may be practiced
without such details. In other instances, well known methods,
procedures, components, and/or circuitry have been described at a
relatively high-level, without detail, in order to avoid
unnecessarily obscuring aspects of the present teachings. In the
following material, indications of direction, such as "top" or
"left," are merely to provide a frame of reference during the
following discussion, and are not intended to indicate a required,
desired, or intended orientation of the described articles.
[0020] In some applications, heat pipes are limited to a small
number of components, such as a central processing unit (CPU).
Thus, other components are simply left to be air cooled, with or
without the assistance of a heat spreader or heat sink(s), and do
not realize benefits available from the high thermal conductivity
of a heat pipe, such as improved component lifespan or performance.
In assembling or disassembling (for example, for repair or
maintenance of a device or system) an electronic system using heat
pipes, heat pipes can present some difficulties--especially if
there are separate heat pipes that need to be routed through the
system. As a result, such system often use simple routes for heat
pipes, to avoid or reduce such assembly or disassembly issues.
[0021] FIG. 1A illustrates an external top isometric view of a
fully assembled example heat transfer device 100 embodying aspects
of techniques described herein. Much as noted previously, the
orientation of the heat transfer device 100 illustrated in FIG. 1A
is not intended to indicate a required, desired, or intended
orientation for the heat transfer device 100. For example, although
FIG. 1A illustrates heat transfer device 100 in a substantially
horizontal orientation, in normal use it may be used in a more
vertical orientation (and the internal structure of the heat
transfer device 100 may be optimized for such orientations, such as
using gravity to increase mass flow), or in essentially any other
orientation. Additionally, although FIG. 1A illustrates heat
transfer device 100 as having a substantially parallelepiped form,
this is merely an example form.
[0022] The heat transfer device 100 includes a top wall 110
providing a major surface wall on a top side of the heat transfer
device 100. In this example, the top wall 110 is substantially
continuous. Preferably the top wall 110 includes a material with a
high thermal conductivity (for example, having a thermal
conductivity greater than 150 W/mK). The top wall 110 includes a
first condenser region 182 and a second condenser region 184, which
will be discussed in more detail below.
[0023] The heat transfer device 100 also includes a front side wall
130 providing a minor surface wall on a front side of the heat
transfer device 100. In this example, the front side wall 130 is
substantially continuous. The front side wall 130 may include
substantially similar materials as the top wall 110, a bottom wall
120 of the heat transfer device 100 (not visible in FIG. 1A), or
one or more of the other side walls 140, 150, and 160, or may
include a different material, including a material without a high
thermal conductivity. In the example illustrated in FIG. 1A, the
front side wall 130 is substantially perpendicular to the top wall
110. The heat transfer device 100 also includes a left side wall
150 providing a minor surface wall on a left side of the heat
transfer device 100. In this example, the left side wall 150 is
substantially continuous. The left side wall 150 may include
substantially similar materials as the top wall 110, the bottom
wall 120, or one or more of the other side walls 130, 140, and 160,
or may include a different material, including a material without a
high thermal conductivity. In the example illustrated in FIG. 1A,
the left side wall 150 is substantially perpendicular to the top
wall 110 and the front side wall 130.
[0024] FIG. 1A illustrates locations of a plurality of
cross-sections, including a first cross-section labeled "2A" along
a Y-Z oriented plane and illustrated in FIG. 2A, a second
cross-section labeled "2D" along a first X-Z oriented plane passing
through the first condenser region 182 and illustrated in FIG. 2D,
and a third cross-section labeled "2E" along a second X-Z oriented
plane passing through the second condenser region 184 and
illustrated in FIG. 2E.
[0025] FIG. 1B illustrates an exploded bottom isometric view of the
heat transfer device 100 illustrated in FIG. 1A. In FIG. 1B, the
heat transfer device 100 has been rotated 180 degrees about the Y
axis with respect to the orientation shown in FIG. 1A. For
convenience of illustration and discussion, only walls 110, 120,
130, 140, 150, 160, and 170 are illustrated in FIG. 1B, and certain
internal features, such as wicks, are not illustrated. It is noted
that although walls 110, 120, 130, 140, 150, 160, and 170 are
illustrated as discrete pieces in FIG. 1B, and the below
description discusses walls 110, 120, 130, 140, 150, 160, and 170
being coupled together, this is not intended to suggest that the
heat transfer device 100 is or should be assembled from such
discrete pieces (such as by welding them together). For example,
two or more of the walls 110, 120, 130, 140, 150, 160, and 170
might be formed together by casting a mold, or forging or stamping
them from a single piece of metal.
[0026] The heat transfer device 100 includes the bottom wall 120
providing a major surface wall on a bottom side of the heat
transfer device 100. In this example, the bottom wall 120 is
substantially continuous. The bottom wall 120 may include a
material with a high thermal conductivity, and may include
substantially similar materials as the top wall 110. The bottom
wall 120 includes a first evaporator region 192 and a second
evaporator region 194, which will be discussed in more detail
below. In the example illustrated in FIGS. 1A and 1B, the bottom
wall 120 is substantially parallel to the top wall 110, and the
lengths of each of the edges 122, 124, 126, and 128 for the bottom
wall 120 are substantially equal to the lengths of the edges 112,
114, 116, and 118 of the top wall 110, respectively.
[0027] The heat transfer device 100 also includes a back side wall
140 providing a minor surface wall on a back side of the heat
transfer device 100. In this example, the back side wall 140 is
substantially continuous. The back side wall 140 may include
substantially similar materials as the top wall 110, the bottom
wall 120, or one or more of the other side walls 130, 150, and 160,
or may include a different material, including a material without a
high thermal conductivity. In the example illustrated in FIGS. 1A
and 1B, the back side wall 140 is substantially perpendicular to
the top wall 110 and substantially parallel to the front side wall
130. The heat transfer device 100 also includes a right side wall
160 providing a minor surface wall on a right side of the heat
transfer device 100. In this example, the right side wall 160 is
substantially continuous. The right side wall 160 may include
substantially similar materials as the top wall 110, the bottom
wall 120, or one or more of the other side walls 130, 140, and 150,
or may include a different material, including a material without a
high thermal conductivity. In the example illustrated in FIGS. 1A
and 1B, the right side wall 160 is substantially perpendicular to
the top wall 110 and the front side wall 130, and substantially
parallel to the left side wall 150.
[0028] The heat transfer device 100 also includes an interior
dividing wall 170 which, in the example illustrated in FIGS. 1A and
1B, divides an interior of the heat transfer device 100 into two
separate chambers: a left chamber 102 positioned between the
dividing wall 170 and the left side wall 150, and a right chamber
104 positioned adjacent to the left chamber 102 along a length of
the bottom wall 120 in the direction of the Y axis. Left chamber
102 and right chamber 104 each function as, and each may each be
referred to as, a vapor chamber and/or a heat pipe. Examples of
vapor chambers are described in U.S. Patent Application Publication
No. 2015/0346784 (published on Dec. 3, 2015), which is incorporated
herein by reference in its entirety. In the example illustrated in
FIGS. 1A and 1B, the left chamber 102 is immediately adjacent to
the right chamber 104. The left chamber 102 and the right chamber
104 are not indicated in FIG. 1B, but are illustrated in FIGS. 1C,
2A, 2D, and 2E. In the example illustrated in FIGS. 1A and 1B, the
dividing wall 170 is substantially perpendicular to the top wall
110, bottom wall 120, the front side wall 130, and the back side
wall 140. The dividing wall 170 may include substantially similar
materials as any of the other walls 110, 120, 130, 140, 150, and
160, or may include a different material. In some implementations,
the dividing wall 170 includes a material with a low thermal
conductivity to reduce thermal crosstalk between the left chamber
102 and the right chamber 104. In the example illustrated in FIGS.
1A and 1B, the walls 110, 120, 130, 140, 150, 160, and 170 are each
plates of uniform thickness (although the wall are not necessarily
the same thicknesses).
[0029] The left chamber 102 and the right chamber 104 are each
hermetically sealed (or "hermetic") in ordinary operation, both
from the external environment outside of the heat transfer device
100 and from one another. Sealing of the walls 110, 120, 130, 140,
150, 160, and 170 may be performed using, for example, welding
(including, but not limited to, resistance heat welding, laser
welding, ultrasonic welding, friction welding, stir friction
welding), brazing, or other bonding techniques. Welding for the
interior dividing wall 170 may be visible on the exterior of heat
transfer device 100. Performance for such hermetic sealing may be,
for example, a loss of no more than 1% per year of a working fluid
sealed within a chamber. Once fully assembled, as illustrated in
FIG. 1A, the heat transfer device 100 is hermetically sealed along
each of the edges 122, 124, 126, 128, 132, 134, 136, 138, 142, 144,
146, 148, 152, 154, 156, 158, 162, 164, 166, 168, 172, 174, 176,
and 178.
[0030] FIG. 1C illustrates another exploded bottom isometric view
of the heat transfer device 100 illustrated in FIGS. 1A and 1B,
with only the bottom wall 120 removed from the remaining walls. In
this view, the left chamber 102 defined by the walls 110, 120, 130,
140, 150, and 170 is shown, and the right chamber 104 defined by
the walls 110, 120, 130, 140, 160, and 170 is shown. Additionally,
FIG. 1C illustrates aspects of a method of making the heat transfer
device 100, in which walls 110, 130, 140, 150, 160, and 170 are
integrated, an interior surface of the bottom wall 120 is processed
to define structures thereon (such as wicks), the bottom wall 120
is attached to the remaining walls 110, 130, 140, 150, 160, and
170, and hermetic sealing of the chambers 102 and 104 is
completed.
[0031] FIG. 2A illustrates a cross-section view, corresponding to
the cross-section labeled "2A" in FIG. 1A, of the heat transfer
device 100 illustrated in FIGS. 1A, 1B, and 1C. In this
illustration, the left chamber 102 and the right chamber 104 are
each hermetically sealed as discussed above. A first heat transfer
medium is disposed within the hermetically sealed left chamber 102,
and is responsible for transferring heat received at the first
evaporator region 192 to the first condenser region 182. Although
in some examples the first heat transfer medium may be in a solid
phase when the left chamber 102 is not being operated, the first
heat transfer medium may be referred to as a "working fluid," as in
operation heat is transferred via transitions between a liquid
phase 230 and a vapor phase 235 of the first heat transfer medium.
Suitable materials for the first heat transfer medium at the
relatively lower temperatures involved with consumer electronics
include, but are not limited to, water, ammonia, pentane, ethanol,
methanol, Flutec PP2, Flutec PP9, carbon tetrachloride, benzene,
acetone, isopropanol, toluene, and heptane. Similarly, a second
heat transfer medium, much as described above for the first heat
transfer medium, is disposed within the hermetically sealed right
chamber 104, and in operation transitions between a liquid phase
232 and a vapor phase 237. In some implementations, the first heat
transfer medium may be different than the second heat transfer
medium to achieve different heat transfer characteristics between
the left chamber 102 and the right chamber 104. It is noted that in
some embodiments of the heat transfer device 100, left chamber 102
may not yet have been filled with the first heat transfer medium
and right chamber 104 may not yet have been filled with the second
heat transfer medium.
[0032] Additionally, FIG. 2A illustrates wicks 210 and 220, which
were not illustrated in FIGS. 1A, 1B, and 1C. Although FIG. 2A
illustrates an example in which wick 210 covers the entire interior
surface of the left chamber 102 and wick 220 covers the entire
interior surface of the right chamber 104, in other examples wick
210 and/or wick 220 may be present on only a portion of the
interior surfaces of their respective chambers 102 and 104. For
example, if the second condenser region 184 and the second
evaporator region 194 were both positioned on the bottom wall 120,
it might be suitable for wick 220 to only be present on the
interior surface of the bottom wall 120. Wick 210 is arranged to
transport the liquid phase 230 by capillary forces to first
evaporator region 192. Wick 220 is arranged to transport the liquid
phase 232 by capillary forces to second evaporator region 194.
[0033] There are many materials, structures, arrangements and
combinations of structures, and techniques for forming such
structures that are suitable for wicks 210 and 220. Wick 210 may
include one or more porous media that may be attached to one or
more interior surfaces of the left chamber 210, such as, but not
limited to, a mesh (such as a woven metal wire mesh), a twill (such
as a woven metal twill fabric), a felt (such as a metal metallic
felt), a metallic foam, and knitted ceramic fibers. Each porous
medium may be of a selected pore size or average pore size, which
may be selected to achieve desired mass flow rate performance
characteristics. A portion of wick 210 may be formed by adding
material to a bulk material for one or more of the walls 110, 120,
130, 140, 150, and 170 that define the left chamber 102. In one
example, a porous medium may be formed directly on an interior
surface of the left chamber 102, such as by sintering a metallic
powder of a selected particle size. In another example, structures
may be added using lithographic techniques. A portion of wick 210
may be formed by selectively removing or displacing portions of a
bulk material for one or more of the walls 110, 120, 130, 140, 150,
and 170. In one example, channels or arteries of selected sizes and
arrangements may be formed in bottom wall 120 to increase a flow
rate of liquid phase 230. U.S. Patent App. Pub. No. 2006/0213648
(published on Sep. 28, 2006), which is incorporated herein by
reference in its entirety, describes examples of applying a mold or
a roller under pressure to a substrate material to form grooves
therein. In another example, microlithographic techniques,
including but not limited to photolithographic methods or "direct
writing" methods such as selective laser melting (SLM), may be used
to selectively form capillary structures. U.S. Pat. No. 8,807,203
(issued on Aug. 19, 2014), which is incorporated herein by
reference in its entirety, describes examples etching a titanium
substrate to form pillars for driving a liquid by capillary forces.
Hydrophobic or hydrophilic materials may be selectively applied to
one or more interior surfaces of the left chamber 102 to modulate
flow characteristics of the wick 210. For example, a capillary
structure may receive a surface treatment that increases its
hydrophilicity, or a portion of the interior surfaces of the left
chamber 210 without capillary structures may receive a surface
treatment that increases their hydrophobicity. Surface roughness
may be selectively controlled on portions of the interior surfaces
of the left chamber 210 to control locations at which condensation
or accumulation of the liquid phase 230 occurs. In some portions,
wick 210 may include multiple layers of wicking structures; for
example, channels covered by a porous medium or multiple layers of
porous media with different pore sizes. Wick 210 may include
multiple wicking structures that are not in direct contact with
each other. Similar options are also available for wick 220.
Different structures, arrangements of structures, and/or materials
may be used for wick 210 and wick 220.
[0034] The left chamber 102 includes the first evaporator region
192, which includes a region of the bottom wall 120 and a region of
the wick 210 immediately adjacent to that region of the bottom wall
120. The first evaporator region 192 may be referred to as an
"evaporator" or an "evaporator portion." The left chamber 102
includes the first condenser region 182, which includes a region of
the top wall 110 and a region of the wick 210 immediately adjacent
to that region of the top wall 110. The first condenser region 182
may be referred to as a "condenser" or a "condenser portion."
Although only one condenser region 182 and only one evaporator
region 192 are illustrated for left chamber 102, in some examples
the left chamber 102 may include multiple evaporator regions and/or
multiple condenser regions. Each condenser region and evaporator
region included in the left chamber 102 may be positioned on any of
the walls 110, 120, 130, 140, and 150 defining the left chamber
102. In some examples or under some conditions, a portion of the
dividing wall 170 may function as a condenser region. In some
examples, a condenser region and evaporator region may be
positioned on a same wall or surface of the left chamber 102; for
example, first condenser region 182 and first evaporator region 192
might both be positioned on the bottom wall 120. Evaporator
regions, such as second evaporator region 194, and condenser
regions, such as second condenser region 184, included in the right
chamber 104 may be similarly arranged.
[0035] In normal operation, as heat is generated by a heat source
240 (illustrated in dashed lines) that is thermally coupled to
first evaporator region 192, the first evaporator region 192
(including respective regions of bottom wall 120 and wick 210)
transfers the heat to the liquid phase 230 contained in the wick
210. In this arrangement, the heat source 240 is arranged to
vaporize the liquid phase 230, with the heat generated by the heat
source 240 causing a transition of the first heat transfer medium
from its liquid phase 230 to its vapor phase 235, transferring the
heat from heat source 240 through the latent heat of vaporization.
The evaporation of liquid phase 230 from the wick 210 at the first
evaporator region 192 causes a void which creates a capillary force
through surface tension that draws the liquid phase 230 through the
wick 210, transporting the liquid phase 230 to the first evaporator
region 192. Thus, the wick 210 allows for continuous replenishment
of the liquid phase 230 for first evaporator region 192, thereby
sustaining a continuous evaporation-condensation cycle. The vapor
phase 235 is transported, through a cavity within the left chamber
102 not occupied by wick 210 or other structures, to first
condenser region 182. At first condenser region 182, the vapor
phase 235 condenses back into its liquid phase 230, releasing the
latent heat of vaporization at first condenser region 182.
[0036] The heat source 240 may also be referred to as a "heat
generating component" of "heat generating element". For example, an
electronic device or system may include various electronic
components that generate heat during operation, as previously
discussed. The electronic component may be attached to a substrate
such as a printed circuit board (PCB). The electronic component may
include or be included in a package or chip carrier providing
mechanical connections, electrical connections, and/or protection,
such as, but not limited to, a ball grid array (BGA) surface-mount
packaging or a through-hole packaging.
[0037] A heat rejection device 260 is thermally coupled to the
exterior of the top wall 110 at the first condenser region 182.
Heat rejection may also be referred to as "heat dissipation." To
improve heat transfer, a thermal interface material (TIM), such as
a thermally conductive grease or mastic, may be applied at a
contact between heat source 240 and first evaporator region 192
and/or at a contact between heat rejection device 260 and first
condenser region 182. The heat rejection device 260 may be arranged
in various ways to accept, store, and dissipate heat that is
communicated from the first condenser region 182 to the heat
rejection device 260. Generally, the heat rejection device 260 as a
heat exchanger that uses fins, pins, and/or other mechanical
structures to increase a surface area in contact with air or
another cooling medium to facilitate heat dissipation. In some
implementations, an external surface of a system housing may be
used to perform heat rejection via a thermally conductive metal
surface. One possible benefit of the two chambers 102 and 104 is
that one chamber may be arranged to maintain that external surface
at a safe or comfortable temperature for contact by a user, while
the other chamber is operated with a higher temperature. In some
examples, a heat pipe or a vapor chamber be used as heat rejection
device 260. In some examples, a single heat rejection device may be
coupled to multiple condenser regions included in one or more vapor
chambers, such as a single heat sink shared by first and second
condenser regions 182 and 184. In some examples, a portion of a
heat rejection device may be incorporated into one or more walls of
the left chamber 102.
[0038] In some implementations, a heat rejection device may include
or be arranged in conjunction with a suitable fluid mover that
provides an active cooling mechanism for thermal control. For
example, a heat rejection device 270 coupled to the second
condenser region 184 includes an air-cooled heat sink 272 and an
attached air blower 274. The fluid mover may be selectively enabled
or disabled in response to a temperature. For example, the fluid
mover may be enabled in response to a measured temperature
exceeding a threshold temperature. Rates at which the fluid mover
moves fluid, which may be measured in terms of a rate of fluid
volume over time, may be selectively controlled in response to a
temperature. For example, a rate of air flow generated by blower
274 may be increased in response to an increased measured
temperature to increase a rate of heat rejection by the heat
rejection device 270.
[0039] The blower 274 may be arranged to pull air from an exterior
of a system housing (not illustrated in FIG. 2A) through intake
vents into an interior of the housing. The blower 274 may be
arranged in various ways, such as an axial fan or a centrifugal
blower for moving air. Although examples are described herein in
relation to air cooling, comparable techniques may be used in other
types of fluid cooling systems employing different types of gases
or even liquids. Accordingly, pumps, impellers, different types of
blowers, fans, and other types of fluid movers may be employed in
alternative designs and/or in conjunction with other types of
cooling fluids. Additionally, although a single blower 274 is
illustrated, multiple fluid movers may be employed in various
implementations. Additionally, a single fluid mover may be shared
by two heat rejection devices, such as a first heat rejection
device thermally coupled to a first condenser and a second heat
rejection device thermally coupled to a second condenser.
[0040] The blower 274 may be arranged to disperse air into the
interior of the housing via one or more flow conduits to heat sink
272, and in some embodiments various heat-generating devices
included in the housing. Various types of flow conduits are
contemplated, such as, but not limited to, channels formed or
otherwise included in the housing, arrangements of device elements
such as components and circuit boards, tubes, manifolds, baffles,
and the heat transfer device 100. Cooling air that is drawn into
the housing by the blower 274 operates to cool the system by
convective transfer, which removes heat from the system by heating
the air. The heated air flows to exhaust vents where the heated air
is expelled from the system.
[0041] The term "active," as applied to heat rejection, generally
refers to heat rejection that requires external energy output. One
example of active heat rejection includes removing heat via forced
air convection by using a blower to provide and/or exhaust cooling
air, such as with the heat rejection device 270 illustrated in FIG.
2A. Another example includes removing heat via conduction using a
chiller and a heat exchanger. In contrast, the term "passive," as
applied to heat rejection, generally refers to heat rejection
without requiring external energy output. Example passive heat
rejection techniques include heat rejection via natural convection,
conduction, and/or radiation. In some examples, an active heat
rejecter may selectively be operated in a passive mode as a passive
heat rejecter. For example, a blower may be disabled below a
threshold temperature, and instead rely on passive heat rejection
via unforced air flow through a heat sink.
[0042] Although condensation of the vapor phase 235 may occur at
other regions of the left chamber 102 (for example, due to
radiation, conduction, or convection of heat at other regions), in
ordinary operation a first proportion of more than 50% of the heat
received via one or more evaporator regions included in the left
chamber 102 is transferred out of the heat transfer device 100 via
the one or more condenser regions included in the left chamber 102,
due to heat rejection devices, such as heat rejection device 260,
reducing the thermal resistance at the condenser regions they are
coupled to. In some examples, the first proportion is more than
60%. In some examples, the first proportion is more than 80%. In
some examples, the first proportion is more than 90%. In some
implementations, the heat rejection device 260 is arranged to
receive a second proportion of more than 50% of latent heat
transferred out of the left chamber 102 by condensation of the
vapor phase 235. In some examples, the first proportion is more
than 60%. In some examples, the second proportion is more than 80%.
In some examples, the second proportion is more than 90%. The left
chamber 102 may also receive heat at other regions than its
evaporator regions. In some implementations, a first proportion of
heat received by the left chamber 102 that is received via its one
or more evaporator regions (in the aggregate) in ordinary operation
is more than 50%. In some examples, the first proportion is more
than 60%. In some examples, the first proportion is more than 80%.
In some examples, the first proportion is more than 90%. It is
noted that for many wick implementations, in which a liquid phase
can flow by capillary forces in either direction, the heat transfer
device 100 can transfer heat in a "reverse" direction, with heat
being input at the first condenser region 182 and heat being output
at the first evaporator region 192. In some such implementation,
this "reversed" arrangement may achieve comparable thermal
efficiency to the ordinary "forward" arrangement. The right chamber
104 illustrated in FIG. 2A operates much as described for left
chamber 102, receiving heat from a heat source 250 thermally
coupled to the second evaporator region 194 to transform liquid
phase 232 into vapor phase 237, and transferring a majority of that
received heat out via a heat rejection device 270 thermally coupled
to second condenser region 184.
[0043] The left chamber 102 may operate as a "thermal transformer,"
receiving heat at first evaporator region 192 with a first heat
flux, and ejecting heat at first condenser region 182 with a second
heat flux that is substantially lower than the first heat flux. An
area of contact between the first condenser region 182 and the heat
rejection device 260 can be selected to adjust a ratio between the
first heat flux and the second heat flux, which may affect a
temperature at first evaporator region 192, a temperature at first
condenser region 182, a temperature of vapor phase 235, a
temperature of heat source 240, a temperature of heat rejection
device 260, and/or a temperature of a fluid passed through the heat
rejection device 260. In some examples, the heat rejection device
260 is thermally coupled to first condenser region 182 via a first
amount of surface area of an exterior surface of the left chamber
102, the heat rejection device 270 is thermally coupled to second
condenser region 184 via a second amount of surface area of an
exterior surface of the right chamber 104, and the first surface
area is substantially different than (including being greater than
or less than) the second surface area. In some examples, the
difference is more than 30%. In some examples, the difference is
more than 60%. In some examples, the difference is more than
100%.
[0044] With the two chambers, left chamber 102 and right chamber
104, two separate "thermal domains" may be established: a first
thermal domain for the left chamber 102 of a first design and a
second thermal domain for the right chamber 104 of a second design
different from the first design. A thermal domain may also be
referred to as a "heat transfer route" or a "heat rejection path."
Each of the first and second thermal domains may be tuned to
achieve different heat transport properties in operation arising
out of differences between the first and second designs. Benefits
of having the two thermal domains include, but are not limited to,
maintaining different component and/or system temperatures with a
single heat transfer device, and/or decoupling heat generated for
one thermal domain from affecting temperatures for other thermal
domains. There are a number of such design differences that may be
employed for such tuning, including, but not limited to: [0045] A
first total internal volume available for vapor transport in a
first chamber being substantially greater than a second total
internal volume available for vapor transport in a second chamber.
For example, excluding wicks and other internal structures. In some
implementations, the first volume is at least 20% greater than the
second volume. In some implementations, the first volume is at
least 50% greater than the second volume. In some implementations,
the first volume is at least 100% greater than the second volume.
[0046] The first heat transfer medium including a different
material than the second heat transfer medium. For example, the
left chamber 102 may contain water and the right chamber 104 may
contain ammonia. [0047] A first total mass of a heat transfer
medium included in a first chamber being substantially greater than
a second total mass of a heat transfer medium included in a second
chamber. This may affect, for example, performance at higher
temperatures. [0048] Different structures for wick 210 and wick
220. For example, the wick 210 and the wick 220 may have
substantially different average thicknesses, have substantially
different average pore sizes, have substantially different
porosities, or include different materials. This may affect, for
example, mass flow rate of a working fluid from a condenser region
to an evaporator region. [0049] Different arrangements for wick 210
and wick 220 on the interiors of their respective chambers 102 and
104. For example, wick 210 may have a first arrangement to improve
transport of liquid phase 232 to evaporator region. [0050] Number,
size, shape, and/or arrangement of internal structures. Structures
may be included within a chamber that facilitate or impede flow of
a liquid phase or a vapor phase. Structures may be included which
maintain an inventory of excess liquid phase material. In some
examples, such structures may include a wick portion to provide an
additional path for supplying a liquid phase to an evaporator
portion. [0051] Difference in wall and/or wick thicknesses at
evaporator regions, which may affect thermal resistance and rate of
evaporation at evaporator regions. [0052] Difference in wall and/or
wick thicknesses at condenser regions, which may affect thermal
resistance and rate of condensation at condenser regions. [0053]
Chamber shapes, which may affect vapor phase and/or liquid phase
flow rates. For example, a reduced cross-sectional area for vapor
phase flow can reduce and/or limit thermal throughput of a vapor
chamber. For example, internal chamber heights may be different or
varied differently.
[0054] FIG. 2B illustrates an example graph of temperatures over
time for the two thermal domains provided by the heat transfer
device 100 illustrated in FIG. 2A and a single thermal domain
provided by a conventional single-chambered vapor chamber. For FIG.
2B, the heat transfer device 100 is included in a system that also
includes, thermally coupled to the heat transfer device 100, the
heat sources 240 and 250 and the heat rejection devices 260 and
270. The system may include additional elements such as, but not
limited to, a chassis, printed circuit boards (PCBs), and/or a
housing. Curve 280 shows temperatures, including the steady-state
temperatures T.sub.L1, T.sub.L2, T.sub.L3, and T.sub.L4, for the
first thermal domain for the left chamber 102 resulting from heat
received by the left chamber 102 from the heat source 240. Curve
285 shows temperatures, including the steady-state temperatures
T.sub.R1, T.sub.R2, T.sub.R3, T.sub.R4, and T.sub.R5, for the
second thermal domain for the right chamber 104 resulting from heat
received by the right chamber 104 from the heat source 250 over the
same period of time as curve 280. Over that period of time, rates
of heat generated by the heat sources 240 and 250 changes over
time, and the curves 280 and 285 reflect these changes in heat
output. Curve 280 and/or curve 285 may reflect changes in levels of
operation of active heat rejection by heat rejection device 260
and/or heat rejection device 270; for example, a blower may be
enabled or its air flow rate varied in response to temperature.
Curve 290 shows temperatures, including the steady-state
temperatures T.sub.S1, T.sub.S2, T.sub.S3, T.sub.S4, and T.sub.S5,
in an example in which the system has a conventional
single-chambered vapor chamber in place of the heat transfer device
100, with the heat sources 240 and 250 and the heat rejection
devices 260 and 270 similarly arranged and all thermally coupled to
the single-chambered vapor chamber. For curve 290, the heat sources
240 and 250 generate heat in the same amounts and at the same
relative times as for curves 280 and 285, and heat rejection
devices 260 and 270 are also operated (including changes in levels
of active heat rejection) as for curves 280 and 285.
[0055] Curve 280 may be a temperature measured at a first point
that is associated with the first thermal domain and located in,
on, or adjacent to the system. Examples of such points include, but
are not limited to; heat source 240 (the temperature of which may
be measured at, or inferred by a measurement at, a position in, on,
or adjacent to heat source 240); bottom wall 120 at or adjacent to
first evaporator region 192; a position in the interior of the left
chamber 102 where vapor phase 235 is present (for example, around
the first evaporator region 192, around the first condenser region
182, or a point between the first evaporator region 192 and first
condenser region 182); top wall 110 at or adjacent to first
condenser region 182; heat rejection device 260 (the temperature of
which may be measured at, or inferred by a measurement at, a
position in, on, or adjacent to heat rejection device 260); within
a fluid (such as air) output and heated by heat rejection device
260, including at our near an exhaust vent of the system; an
element of the system, such as an electronic component, receiving
heat output by the first thermal domain; and a portion of a human
body, including skin, receiving heat output by the first thermal
domain. Curve 280 may be an average temperature, including, but not
limited to, an average of temperatures measured at multiple points
such as those described above for the first point, an average
temperature of a surface area, or an average temperature within a
volume (for example, an average temperature of vapor phase 235).
One or more of such points or average temperatures may be of
particular interest for designing, implementing, and operating the
system, such as, but not limited to, to avoid exposing a user to
uncomfortable or unsafe temperatures, or to avoid exceeding a
maximum temperature for a component. Curve 290 may be a temperature
measured at a second point, different that the first point, that is
associated with the second thermal domain and located in, on, or
adjacent to the system, or an average temperature, much as
discussed above for curve 280. In general, it is preferred that the
temperatures measured for curve 280 are more significantly affected
by the first thermal domain than the second thermal domain, and
that the temperatures measured for curve 285 are more significantly
affected by the second thermal domain than the first thermal
domain.
[0056] The temperatures may be measured while operating the system
under a condition of interest, or a condition simulating a
condition of interest. For example, for an electronic device that
is intended to be worn by a user, measurements may be performed
while the device is worn by a person or mounted on an apparatus
simulating aspects relevant to thermal performance, as it may be
more difficult for the device the reject heat while being worn. The
temperatures may be measured while operating the system in a
controlled environment, which may reflect an ordinary operating
environment or a more extreme environment. Temperatures may be
measured while operating the system or a portion of the system in a
selected manner. For example, particular functions of the system
may be selectively enabled, a processor may be operated at a
selected performance level or clock speed, or a portion of the
system may be operated in a selected mode or at a selected level.
The selected manner may include a portion of the system being
operated in an atypical manner, such as with a blower disabled, to
ensure thermal performance meets a desired target under "worst
case" conditions. In some examples, heat sources 240 and 250 may be
operated so as to supply substantially equal heat loads to their
respective evaporator regions 192 and 194.
[0057] Properties of the heat transfer device 100 and/or the system
in which the heat transfer device is included may be measured in
terms of "steady-state" operating temperatures and/or measured at a
time that a steady state operating temperature or temperatures have
been reached for the first thermal domain and/or the second thermal
domain. This may also be referred to as a "thermal steady-state."
When a steady-state temperature has been reached for a thermal
domain, that thermal domain and the vapor chamber included therein
may be referred to as being operated in a steady-state. For
purposes of this disclosure, the terms "steady-state operation" and
"steady-state operating" do not apply to circumstances that an
electronic system, in which the heat transfer device 100 is
included, is not receiving power, is turned off, is in a sleep
state (such as ACPI global state G1), or other such circumstances
in which no or very little heat is being generated by heat source
240 and/or heat source 250. For example, although an unpowered
electronic device may match a temperature of its surroundings (for
example, "room temperature") and remain at or around that
temperature for a period of time, the device is not in
"steady-state operation" or at a "steady-state operating
temperature" during that period of time.
[0058] As noted above, curves 280 and 285 reflect changes in
temperatures for their respective first and second thermal domains
in response to changes in heat generated by heat sources 240 and
250. As a nonlimiting example, in a heat source including a
microprocessor, increased heat generation may occur during periods
of more intensive processing and/or operation at increased clock
rates. At time t0, neither of the heat sources 240 and 250 are
generating heat. For example, the heat sources 240 and 250 may be
included in an electronic device that is turned off. At time t1,
heat sources 240 and 250 begin generating heat which is received by
their respective left chamber 102 and right chamber 104, and the
temperatures measured for curves 280 and 285 begin increasing. For
example, power may be applied to the system. In this example, from
about time t1 to about time t4, heat source 240 generates a heat
load at a first level and heat source 250 generates a heat load at
a second level. From time t1 to about time t2, the temperature at
the first point for curve 280 is transient (or "in a transient
state" or "in transition"), and continues to increase until it
reaches a steady-state temperature T.sub.L1 about time t2. From
about time t2 to about time t4, the first thermal domain and the
left vapor chamber 102 may be referred to as operating in a
steady-state. Likewise, beginning at time t1, the temperature at
the second point for curve 285 is transient for a longer time until
it reaches a steady-state temperature T.sub.R1 about time t3. From
about time t3 to about time t4, the second thermal domain and the
right vapor chamber 104 may be referred to as operating at a
thermal steady-state. During periods of time that all of the
thermal domains for the heat transfer device 100 (in this example,
both chambers 102 and 104) are at thermal steady-state, such as
from about time t3 to about time t4, the heat transfer device 100
may be referred to as operating in a thermal steady-state, and, in
some examples, the system may also be referred to as operating in a
thermal steady-state. The steady-state temperature T.sub.R1 is
substantially higher than the steady-state temperature T.sub.L1.
For example, in a consumer electronic device, a difference between
steady-state temperature T.sub.R1 and the steady-state temperature
T.sub.L1 may be at least 5.degree. C., at least 10.degree. C., or
at least 20.degree. C.
[0059] At about time t4, both heat sources 240 and 250 increase
their rates of heat generation. For example, the heat source 240
may include a microprocessor and the heat source 250 may include a
graphics processing unit (GPU), both of which may be operated more
intensively by the system from about time t4 to about time t6. Both
curves 280 and 285 are in transition periods in which temperatures
increase from about time t4 to about time t5. At about time t5, the
first point reaches a steady-state temperature T.sub.L2, and the
second point reaches a steady-state temperature T.sub.R2. At about
time t6, both heat sources 240 and 250 decrease their rates of heat
generation to levels below those at about time t3, and temperatures
transition downward. For example, heat sources 240 and 250 may have
reduced their intensities of operation. Heat source 240 remains at
its rate of heat generation until about time t11, and the first
point is at a steady-state temperature T.sub.L3 from about time t7
to about time t11. Alternatively, heat source 240 may maintain the
same rate of heat generation from about time t4 to about time t11,
and instead at about time t6 heat rejection device 260 may increase
its rate of heat rejection, such as by activation of a blower to
change from passive heat rejection to active heat rejection (for
example, temperature T.sub.L2 may be above a target temperature for
the first point). Heat source 250 remains at its rate of heat
generation until about time t9, and the second point is at a
steady-state temperature T.sub.R3 from about time t8 (after time
t7) to about time t9. At about time t9, heat source 250 increases
its rate of heat generation, and the curve 285 transitions upward
until the second point reaches a new steady-state temperature
T.sub.R4 at about time t10. During a first time period from about
time t8 to about time t9 and a second time period from about time
t10 to time t11, the heat transfer device is in thermal
steady-state operation. At about time t11, both heat sources 240
and 250 decrease their rates of heat generation to levels below
those at about time t8. Temperatures from curves 280 and 285 both
transition downward until reaching respective steady-state
temperatures T.sub.L4 and T.sub.R5 at about time t12.
[0060] Curve 290 provides a comparative illustration of performance
of the conventional single-chambered vapor chamber in place of the
heat transfer device 100. Curve 290 may reflect temperatures
recorded at the first point and/or the second point. For example,
where the first point measures a temperature of the heat source 240
and the second point measures a temperature of the heat source 250,
those two temperatures may be essentially the same due to the
isothermal nature of the single vapor chamber to which they are
both thermally coupled. As illustrated in FIG. 2B, the temperatures
for curve 290 are consistently above the temperatures for curve
280, including during periods of thermal steady-state.
Additionally, from at time t9 to about t10, the temperature for
curve 290 increases due to increased heat generation by heat source
250. In contrast, as illustrated by curves 280 and 285, the first
thermal domain is thermally decoupled from the second thermal
domain (although there may be some degree of "thermal crosstalk" in
some examples, such as via the dividing wall 170), and increased
heat generation by the heat source 250 has a substantially reduced
effect on the temperature at the second point.
[0061] Differences in heat transport properties between the first
and second thermal domains may be observed and/or measured in
various ways. For example, for the heat transfer device 100: [0062]
With heat transfer device 100 operating in a thermal steady-state,
a vapor temperature of the vapor phase 235 is substantially
different than (including being greater than or being less than) a
vapor temperature of the vapor phase 237. The difference may be
substantial where the difference is significantly greater than
normal temperature variation due to losses in vapor flow. In some
examples, the difference is at least 5.degree. C. In some examples,
the difference is at least 10.degree. C. In some examples, the
difference is at least 20.degree. C. The vapor temperatures may be
average vapor temperatures within each chamber 102 and 104. The
vapor temperatures may be measured around first and second
evaporator regions 192 and 194. The vapor temperatures may be
measured around first and second condenser regions 182 and 184. The
vapor temperatures may be measured in corresponding adiabatic
portions of the chambers. the thermal steady-state may be with
substantially equal heat loads being supplied by heat sources 240
and 250 at their respective evaporator regions 192 and 194. The
thermal steady-state may be with a system including the heat
transfer device 100 being operated nominally (which may be referred
to as a "nominal powered on thermal steady-state"), or being
continuously operated for a minimum amount of time, such as, but
not limited to, 10 minutes, 20 minutes, 30 minutes, 1 hour, or 2
hours. The thermal steady-state may be with a system including the
heat transfer device 100 being and having been powered on for a
minimum period of time, such as, but not limited to, 10 minutes, 20
minutes, 30 minutes, 1 hour, or 2 hours. [0063] With heat transfer
device 100 operating in a thermal steady-state, a first
steady-state temperature at a first point for the first thermal
domain is substantially different than (including being greater
than or being less than) a second steady-state temperature at a
corresponding second point for the second thermal domain. In some
examples, the difference is at least 5.degree. C. In some examples,
the difference is at least 10.degree. C. In some examples, the
difference is at least 20.degree. C. Various measurement points for
thermal domains are discussed above in connection with FIG. 2B. In
an example, the first point is heat source 240 and the second point
is heat source 250. In an example, the first point is heat
rejection device 260 and the second point is heat rejection device
270. For example, the heat transfer device 100 may be included in
an electronic assembly, first point a user-exposed surface of heat
rejection device 260, and the electronic assembly arranged such
that the first steady-state temperature is at or below 40.degree.
C. (making user contact safe or comfortable) and the second
steady-state temperature is at or above 50.degree. C. In another
example, the first point is within a fluid heated and output by
heat rejection device 260 and the second point is within a fluid
heated and output by heat rejection device 270. In an example, an
electronic assembly including the heat transfer device 100 is
arranged such that, when the electronic assembly is at a nominal
powered on thermal steady-state, a user-exposed surface of the
first heat rejection structure has a steady-state temperature at or
below a 40.degree. C. (or another temperature selected as safe or
comfortable for user contact), and a temperature of the second heat
rejection structure steady-state temperature of at or above
50.degree. C. (or at least 10.degree. C. higher than the
steady-state temperature of the user-exposed surface). the thermal
steady-state may be with substantially equal heat loads being
supplied by heat sources 240 and 250 at their respective evaporator
regions 192 and 194. The thermal steady-state may be with a system
including the heat transfer device 100 being operated nominally
(which may be referred to as a "nominal powered on thermal
steady-state"), or being continuously operated for a minimum amount
of time, such as, but not limited to, 10 minutes, 20 minutes, 30
minutes, 1 hour, or 2 hours. The thermal steady-state may be with a
system including the heat transfer device 100 being and having been
powered on for a minimum period of time, such as, but not limited
to, 10 minutes, 20 minutes, 30 minutes, 1 hour, or 2 hours. [0064]
When the left chamber 102 is operating in a thermal steady-state at
a first steady-state vapor temperature, a first heat transfer rate
via the first heat transfer medium is substantially different than
(including being greater than or being less than) a second heat
transfer rate via the second heat transfer medium when the right
chamber 104 is operating in a thermal steady-state at the first
steady-state vapor temperature.
[0065] Characterization, computer modeling, and computer simulation
may be used to guide design decisions to achieve targets for heat
transfer properties under various operating conditions, and to
investigate various structures and geometries for the left chamber
102 and the right chamber 104. For example, finite element
software, such as COMSOL Multiphysics by COMSOL, Inc. of Stockholm,
Sweden, may be used for numerical simulation of, among other
things, capillary-driven fluid motion (for example, via surface
tension modeling and the Navier-Stokes equation), vapor-phase
transport (for example, via the Navier-Stokes equation),
evaporation, condensation, heat transfer (including conduction,
radiation, and convection for structures and heat transfer media),
temperature distribution, heat adsorption, and stress analysis.
Such approaches for design are not limited to the heat transfer
device 100, but may further involve and/or account for other
elements of a system in which the heat transfer device is included
(as such elements, particularly in a densely constructed system,
can affect heat transfer) and/or environmental conditions of such a
system.
[0066] FIG. 2C illustrates an example of an alternative embodiment
in which a liquid phase of a heat transfer material may flow
between two hermetic chambers included in the heat transfer device
100 illustrated in FIG. 2A. In this example, the first heat
transfer material is the same as the second heat transfer material
(for example, water), and at least one channel 172 is included in
the interior dividing wall 170 through which a liquid phase of a
heat transfer medium by pass between the left chamber 102 and the
right chamber 104. The heat transfer device illustrated in FIG. 2C
is arranged such that the liquid phase of the heat transfer medium
will pass through the channel 172, but the vapor phase of the heat
transfer medium will not pass through the channel 172 due to the
liquid phase being present in and around the channel 172. In the
cross-section illustrated in FIG. 2C, dividing wall 170 does not
reach the bottom wall 120; however, in nearby cross-sections wall
170 extends completely between the top wall 110 and the bottom wall
120. In some examples, as illustrated in FIG. 2C, a wick or porous
material effective for transporting the liquid phase by capillary
forces is disposed in the channel 172. In some examples, as
illustrated in FIG. 2C, the channel 172 is completely covered by
the wick 210 disposed in the left channel 102. In some examples, as
illustrated in FIG. 2C, the channel 172 is completely covered by
the wick 220 disposed in the left channel 104. In some examples, a
portion of the channel 172 may be provided in the bottom wall 120.
In some examples, the channel 172 may be provided in a middle
portion of the dividing wall 170. A benefit of including the
channel 172 is that a dryout condition, in which an inventory of
the liquid phase becomes unavailable to an evaporator region and
the evaporation-condensation cycle becomes stalled or broken and
heat transport through a chamber is interrupted, can be avoided by
making a greater inventory of the liquid phase available.
[0067] FIG. 2D illustrates a cross-section view, corresponding to
the cross-section labeled "2D" in FIG. 1A, of the heat transfer
device 100 illustrated in FIGS. 1A, 1B, 1C, and 2A. The interior of
the left chamber 102 has a low first aspect ratio (substantially
less than 1:1) in a first cross-section (for example, the
cross-section illustrated in FIG. 2A) and a low second aspect ratio
in a second cross-section perpendicular to the first cross-section
(for example, the cross-section illustrated in FIG. 2D). The term
"aspect ratio" refers to a height/width ratio (where the width is
the longer of the two). A width may be measured as a distance along
a linear path or a curvilinear path (for a curved chamber or a
chamber with a complex shape, for example) within an interior of a
chamber and between opposing ends or sides of the chamber. A height
may be an average height along a path used to measure the width (in
some implementations, an internal height may vary within a vapor
chamber). For example, the first aspect ratio may be a ratio of a
height of the left chamber 102 measured along the Z-axis and a
width of the left chamber 102 measured along the Y-axis, and the
second aspect ratio of the left chamber 102 may be a ratio of a
height of the left chamber 102 measured along the same Z-axis and a
width of the left chamber 102 measured along the X-axis. In some
implementations, both of the first and second aspect ratios are
less than 1:4. In some implementations, both of the first and
second aspect ratios are less than 1:8. In some implementations,
both of the first and second aspect ratios are less than 1:16. In
some implementations, both of the first and second aspect ratios
are less than 1:32.
[0068] FIG. 2E illustrates a cross-section view, corresponding to
the cross-section labeled "2E" in FIG. 1A, of the heat transfer
device 100 illustrated in FIGS. 1A, 1B, 1C, 2A, and 2D. As with the
left chamber 102, the interior of the right chamber 104 has a low
third aspect ratio in a third cross-section (for example, the
cross-section illustrated in FIG. 2A) and a low fourth aspect ratio
in a fourth cross-section perpendicular to the third cross-section
(for example, the cross-section illustrated in FIG. 2E). In some
implementations, both of the first and second aspect ratios are
less than 1:4. In some implementations, both of the first and
second aspect ratios are less than 1:8. In some implementations,
both of the first and second aspect ratios are less than 1:16. In
some implementations, both of the first and second aspect ratios
are less than 1:32. In some implementations, all of the first,
second, third, and fourth aspect ratios are less than 1:4. In some
implementations, all of the first, second, third, and fourth aspect
ratios are less than 1:8. In some implementations, all of the
first, second, third, and fourth aspect ratios are less than 1:16.
In some implementations, all of the first, second, third, and
fourth aspect ratios are less than 1:32.
[0069] This description of features, systems, and components is not
intended to be exhaustive and in other embodiments, heat transfer
device 100 may include other features, systems, and/or components.
Moreover, in other embodiments, some of these features, systems,
and/or components could be optional. As an example, instead of
having the five walls 110, 130, 140, 150, and 160, they may be
replaced with a cap-like structure that still provides the two
hermetically sealed left and right chambers 102 and 104 separated
by the dividing wall 170.
[0070] In the embodiments that follow in FIGS. 3-11B, the reader
may understand that the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-2E may be equally applicable to the
following embodiments. Thus, for example, although a heat transfer
device or chamber included therein may not be specifically
described below as including a feature, property, characteristic,
material, and/or arrangement, it may be appreciated that the
details provided above with respect to FIGS. 1A-2E may be
incorporated in any of the following embodiments of FIGS.
3-11B.
[0071] FIG. 3 shows a heat transfer device 300 illustrating
examples of features that may be selectively included in the heat
transfer devices described herein. Additionally, the heat transfer
device 300 may include the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-2E. Heat transfer device 300 has a
substantially curved shape with two major surface walls 310 and
315. In this example, the walls 310 and 315 are substantially
parallel. Other, more complex shapes may be used to accommodate
locations of components and elements within a system including the
heat transfer device 300, as well as desired locations, mechanisms,
and characteristics for heat rejection devices coupled to heat
transfer device 300. For example, this can accommodate a non-planar
or non-parallel arrangement of surfaces of heat sources in contact
with the heat transfer device 300 (for example, top surfaces of
integrated chip (IC) packages. Additionally, heat transfer device
300 may have a more complex "floor plan" than the generally
rectangular examples illustrated thus far. Heat transfer device 300
includes a dividing wall 320, having a complex shape, which
separates a hermetically sealed first chamber 330 located adjacent
to a hermetically sealed second chamber 340, which may be
configured and operated as described for the left and right
chambers 102 and 104 with reference to FIGS. 1A-2E. The complex
shape of dividing wall 320, and its effect on which portions of the
exterior surfaces of heat transfer device 300 correspond to the
first and second chambers 330 and 340, allows for more control and
design flexibility for which thermal domains heat sources are
included in and their locations. The second chamber 340 has
variations in internal height, including a portion 345 having a
greater interior height than other portions of the second chamber
340. More complex variations in internal height may be used for
either of the first and second chambers 330 and 340. Variations in
interior chamber height may be useful for increasing, directing, or
otherwise controlling flow of a vapor phase of a heat transfer
medium sealed in the second chamber 340. For example, the increased
internal height may avoid restrictions in vapor flow for a
condenser region or evaporator region included in the portion
345.
[0072] Heat transfer device 300 includes an aperture 350 passing
therethrough. In this example, aperture 350 passes through the
second chamber 340, but in other examples a single aperture may
pass through multiple chambers. There is sealing around aperture
350 to ensure the second chamber 340 is hermetically sealed.
Although aperture 350 is illustrated with a circular shape, other
and more complex shapes may be used. Aperture 350 may be used for
purposes such as, but not limited to, ensuring accurate positioning
of the heat device 300 in a system, ensuring accurate positioning
of elements of the system (including, for example, heat sources)
relative to the heat device 300, mechanically securing heat
transfer device 300 (including, for example, tapped through holes
for fasteners), mechanically securing elements of the system to the
heat transfer device 300 (including, for example, tapped through
holes for fasteners), allowing a sensor (such as a camera or
microphone) to sense an environment on an opposite side of the heat
transfer device 300, passage of signals and/or power through heat
transfer device 300, providing an improved thermal coupling with a
heat source or heat rejection device, and/or passage of air through
the heat transfer device 300. Heat transfer device 300 also
includes similar, but smaller, apertures 355a and 355b which pass
through the first chamber 330, and which may be arranged and
utilized as discussed for aperture 350.
[0073] The wall 310 includes a convex or protruding portion 360 and
a concave or depressed portion 365. In some examples, there is a
corresponding change in internal chamber height. In some examples,
wall 310 may have an increased thickness at protruding portion 360.
In some examples, wall 310 may have a decreased thickness at
depressed portion 365. Protruding portion 360 and/or depressed
portion 365 may be included in or include an evaporator region or a
condenser region. Protruding portion 360 and/or depressed portion
365, and the extents to which they protrude or are depressed, may
be arranged to accommodate differences in distances between heat
sources from heat transfer device 300 (for example, chips on a
common substrate may be of different heights). The surfaces of
protruding portion 360 and/or depressed portion 365 do not have to
be parallel with a surrounding portion of a chamber wall; for
example, they may be tiled or have complex non-planar surfaces.
Protruding portion 360 may protrude more substantially than
illustrated in FIG. 3 to thermally couple heat transfer device 300
to a heat source or heat rejection device that would otherwise not
be immediately adjacent to heat transfer device 300.
[0074] Mounting structures 370a, 370b, and 370b are included on an
exterior of heat transfer device, which may be used for purposes
such as, but not limited to, ensuring accurate positioning of the
heat device 300 in a system, ensuring accurate positioning of
elements of the system (including, for example, heat sources)
relative to the heat device 300, mechanically securing heat
transfer device 300 (including, for example, tapped through holes
for fasteners), and/or mechanically securing elements of the system
to the heat transfer device 300 (including, for example, tapped
through holes for fasteners). Such mounting structures may be
located on essentially any exterior portion of heat transfer device
300.
[0075] FIG. 4 shows a heat transfer device 400 illustrating
examples of additional features that may be selectively included in
the heat transfer devices described herein. Heat transfer device
400 may include the various features, properties, characteristics,
materials, and/or arrangements as described above with reference to
FIGS. 1A-3. Heat transfer device 400 includes more than two
chambers; specifically, a hermetically sealed first chamber 410,
which is adjacent to a hermetically sealed second chamber 420,
which in turn is adjacent to a hermetically sealed third chamber
430. The first and second chambers 410 and 420 have a shared
dividing wall 440 therebetween, and the second and third chambers
420 and 430 have a shared dividing wall 450 therebetween. Chambers
410, 420, and 430 may be configured and operated as described for
the chambers 102 and 104 with reference to FIGS. 1A-2E and/or the
chambers 330 and 340 with reference to FIG. 3. Heat transfer device
400, as well as other heat transfer devices described herein, may
have two or more chambers, with respective thermal domains each
tuned to achieve target heat transfer properties, of varying sizes,
shapes, and arrangements relative to each other. For example, the
illustrated heat transfer device 400 might be modified to include a
fourth chamber in which the wall 405 becomes an internal dividing
wall, and the fourth chamber is adjacent to all of the chambers
410, 420, and 430. In an example, chamber 430 might be used as a
heat rejection device for chamber 420, with dividing wall serving
as a condenser region for chamber 420 and an evaporator region for
chamber 430.
[0076] Chamber 410 includes internal structures 460a, 460b, 460c,
and 460d; for example, support posts may be provided to
mechanically support or strengthen chamber 410. Chamber 420
includes internal structures 465a, 465b, 465c, 465d, 465e, and
465f. Some or all of the structures may be used for mechanical
support, improving rigidity, directing a liquid phase, or directing
a vapor phase. In an example, one or more of internal structures
460a, 460b, 460c, 460d, 465a, 465b, 465c, 465d, 465e, and 465f may
include wicking material to more directly convey a liquid phase
between opposite sides of their chambers and/or to retain an
inventory of the liquid phase.
[0077] FIG. 5A illustrates an example of a substrate 510 with
electronic components 520 and 525a-525i mounted thereon and/or
therein that are associated with two different thermal domains.
Substrate 510 may be, but is not limited to, a printed circuit
board (PCB) providing mechanical support and electrical connections
(for signaling and/or power, for example) for the electronic
components 520 and 525a-525i. In some examples, electronic
components for a single thermal domain may be across multiple
substrates. In an example, electronic component 520 may be a
microprocessor, GPU, or SoC, and electronic components 525a-525i
may be memory devices (for example, DRAM, flash memory, and/or
phase change memory devices). Electronic component 520 might, for
example, generate substantial amounts of heat energy that
preferably is not delivered to the electronic components 525a-525i.
Conventionally, the solution to such an issue might be to couple
electronic component to a heat pipe, and leave electronic
components 525a-525i to be air cooled. A first edge 521 for
electronic component 520 is spaced apart from a second edge 527b
for electronic component 525b, and a third edge 522 for electronic
component 520 is spaced apart from a fourth edge 527h for
electronic component 525h.
[0078] FIG. 5B illustrates an example of a heat transfer device 530
that is adapted to provide first and second thermal domains for the
electronic components 520 and 525a-525i shown in FIG. 5A. Heat
transfer device 530 may include the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-4. FIG. 5B shows a floor plan of the
heat transfer device 530, with an internal dividing wall 550
between adjacent a hermetically sealed first chamber 540 for the
first thermal domain and a hermetically sealed second chamber 545
for the second thermal domain. The wall 550 is shaped to include
and/or exclude various components and areas for the two thermal
domains. The first chamber 540 includes an evaporator region 560,
which is adapter to be thermally coupled to the electronic
component 520 illustrated in FIG. 5A. The second chamber 545
includes a plurality of evaporator regions 565a-565i adapted to be
thermally coupled to the electronic components 525a-525i
respectively. A first edge 561 for evaporator region 560 is spaced
apart from a second edge 567b for evaporator region 565b, and the
dividing wall 550 is positioned between the first and second edges
561 and 567b. A third edge 562 for evaporator region 560 is spaced
apart from a fourth edge 567h for evaporator region 565h, and the
dividing wall 550 is positioned between the third and fourth edges
562 and 567h.
[0079] FIG. 5C illustrates an example electronic assembly 500 with
the substrate 510 and electronic components 520 and 525a-525i
illustrated in FIG. 5A coupled to the heat transfer device 530
illustrated in FIG. 5B. The electronic assembly may provide or be
included in an electronic system. In electronic assembly 500,
electronic component 520 is thermally coupled to evaporator region
560, and electronic components 525a-525i are thermally coupled to
their respective evaporator regions 565a-565i. In the illustrated
example, the first thermal domain includes condenser regions 570
and 575, which may be thermally coupled to respective heat
rejection devices (not illustrated), and the second thermal domain
includes condenser region 580. By this arrangement, heat generated
by the electronic component 520 and management of that heat is
decoupled from electronic components 525a-525i. Additionally,
electronic components 525a-525i are able to exploit the high
thermal conductivity available with chamber 545 for improved heat
removal. In the example illustrated in FIG. 5C, the first chamber
540 covers the electronic component 560, and the second chamber 545
covers the electronic components 525a-525i. In some examples, as
illustrated in FIG. 5C, the first chamber 540 and/or a bottom wall
of first chamber 540 is not disposed above the electronic
components 525a-525i, and the second chamber 545 is not disposed
above the electronic component 560. Such arrangements ensure
effective thermal coupling of the first chamber 540 to electronic
component 560 and second chamber 545 to electronic components
525a-525i, and also improved thermal decoupling of electronic
component 560 from electronic components 525a-525i.
[0080] FIG. 6A illustrates an example heat transfer device 600 with
a vacuum or thermally insulating material disposed between two
adjacent chambers 610 and 615. Heat transfer device 600 may include
the various features, properties, characteristics, materials,
and/or arrangements as described above with reference to FIGS. 1A-4
and 5B. Much as with the previously described heat transfer
devices, the heat transfer device 600 includes a hermetically
sealed first chamber 610 (for a first thermal domain), with a wick
620 therein, that is positioned adjacent to a hermetically sealed
second chamber 615 (for a second thermal domain), with a wick 625
therein. In the example illustrated in FIG. 6A, the first chamber
610 is spaced apart from the second chamber 615 by a lateral
distance 661. A top wall 640 defines both a top wall for the first
chamber 610 and a top wall for the second chamber 615. A bottom
wall 630 defines both a bottom wall for the first chamber 610 and a
bottom wall for the second chamber 615.
[0081] Instead of the first chamber 610 and the second chamber 615
sharing a single interior dividing wall, as with the wall 170
illustrated in FIGS. 1C and 2A, the first chamber 610 includes a
first dividing wall 650, which is adjacent to, but separated by a
narrow thermally insulating chamber or gap 660 from, a second
dividing wall 655 included in the second chamber 615. In some
examples, a distance between the first and second dividing walls
650 and 655 is less than a height of chamber or gap 660. In some
examples, the chamber or gap 660 may be hermetically sealed with a
full or partial vacuum maintained within the sealed chamber or gap
660. The vacuum may be formed and chamber or gap 660 fully sealed
during a filling procedure for the first chamber 610 and/or the
second chamber 615. In some examples, the chamber or gap may be
filled with a thermally insulating material. The thermal insulation
provided by the chamber or gap 660 reduces "thermal crosstalk"
between the first chamber 610 and the second chamber 620. Although
there may be heat conduction through the walls 630 and 640, this
arrangement substantially improves thermal decoupling of the first
and second chambers 610 and 615 over a shared wall approach.
[0082] FIG. 6B illustrates an example heat transfer device 605 with
a gap 662 between two adjacent chambers 610 and 615. Heat transfer
device 605 may include the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-4, 5B, and 6A. The heat transfer device
605 is arranged much as the heat transfer device 600 illustrated in
FIG. 6A. However, instead of a common wall defining top walls of
both chambers, in FIG. 6B the first chamber 610 includes a top wall
642 that is apart from a top wall 644 included in the second
chamber 615. The bottom wall 630 still defines both a bottom wall
for the first chamber 610 and a bottom wall for the second chamber
615. In the example illustrated in FIG. 6B, the first chamber 610
is spaced apart from the second chamber 615 by a lateral distance
663. In some examples, a distance between the first and second
dividing walls 650 and 655 is less than a height of the first
dividing wall 650 or the second dividing wall 655. The gap 662
between the first and second dividing walls 650 and 655 is left
open and exposed. Although there may be heat conduction through the
wall 630, this arrangement substantially improves thermal
decoupling of the first and second chambers 610 and 615 over a
shared wall approach.
[0083] FIG. 7A illustrates an example heat transfer device 700 with
a vacuum or thermally insulating material disposed between two
adjacent chambers 710 and 715. Heat transfer device 700 may include
the various features, properties, characteristics, materials,
and/or arrangements as described above with reference to FIGS.
1A-4, 5B, and 6A. Much as with the previously described heat
transfer devices, the heat transfer device 700 includes a
hermetically sealed first chamber 710 (for a first thermal domain),
with a wick 720 therein, that is positioned adjacent to a
hermetically sealed second chamber 715 (for a second thermal
domain), with a wick 725 therein. A top wall 740 defines both a top
wall for the first chamber 710 and a top wall for the second
chamber 715. A bottom wall 730 defines both a bottom wall for the
first chamber 710 and a bottom wall for the second chamber 715.
[0084] In FIG. 7A, a chamber or gap 760 is provided that is similar
to the chamber or gap 660 in FIG. 6A, except the chamber of gap 760
provides a separation for only a portion of the area between the
first and second chambers 710 and 715. Chamber or gap 760 may be
described as partially separating the first and second chambers 710
and 715. A partial dividing wall 750 is shared by and provides a
wall defining the first and second chambers 710 and 715. At a top
of the partial dividing wall 750, there is a split into two walls:
a dividing wall 752 that defines the first chamber 710 and a
dividing wall 754 that defines the second chamber 714. Although
FIG. 7A illustrates a `Y` shape for dividing walls 750, 752, and
754, other arrangements of walls may be used to define the chamber
or gap 760. In the example illustrated in FIG. 7A, at the bottom,
the first chamber 710 is spaced apart from the second chamber 715
by a first lateral distance 751 corresponding to a thickness of
dividing wall 750. Beginning at the top of the dividing wall 750,
the lateral distance at which the first chamber 710 is spaced apart
from the second chamber 715 increases to a second lateral distance
761 at the top. This arrangement may be useful where it is desired
for the first and second chambers 710 and 715 to be closer together
on one side of the heat transfer device 700 than can be achieved
with the arrangement illustrated in FIG. 6A; for example, where a
first evaporator region for the first chamber 710 is positioned
very close to a second evaporator region for the second chamber
715, allowing two very closely positioned heat sources to be in
separate thermal domains. Although there may be heat conduction
through the walls 730, 740, and 750, this arrangement improves
thermal decoupling of the first and second chambers 710 and 715
over the shared wall approach illustrated in FIGS. 1C and 2A. In
some examples, the lateral distance between the first and second
chambers 710 and 715 may change more abruptly.
[0085] FIG. 7B illustrates an example heat transfer device 705 with
a gap 762 between two adjacent chambers 710 and 715. Heat transfer
device 705 may include the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-4, 5B, 6A, 6B, and 7A. The heat transfer
device 705 is arranged much as the heat transfer device 700
illustrated in FIG. 7A. However, instead of a common wall defining
top walls of both chambers, in FIG. 7B the first chamber includes a
top wall 742 that is apart from a top wall 744 included in the
second chamber 615. The bottom wall 730 still defines both a bottom
wall for the first chamber 710 and a bottom wall for the second
chamber 715. The gap 762 between the first and second dividing
walls 752 and 754 is left open and exposed. Although there may be
heat conduction through the walls 730 and 750, this arrangement
improves thermal decoupling of the first and second chambers 710
and 715 over the shared wall approach illustrated in FIGS. 1C and
2A. In some examples, the lateral distance between the first and
second chambers 710 and 715 may change more abruptly.
[0086] FIG. 8A illustrates an example of a multi-die package 800
that may be thermally coupled to a heat transfer device (not
illustrated in FIG. 8A) to provide separate thermal domains for
dice included in the multi-die package 800. Multi-die package 800
may also be referred to as a "multi-die chip carrier," "multi-chip
package" or a "system in package." A die may also be referred to as
a "chip" or a "substrate." Multi-die packaging may be used to,
among other things, increase component density, improve
manufacturing yields by reducing die sizes, heterogenous
integration of dice produced using different processes (for
example, different fabrication nodes such as 14 nm and 65 nm, or
different substrate materials such as silicon and gallium nitride),
higher communication bandwidth and/or lower latency between dice,
and integration of dice produced by different vendors (for example,
a logic die and a memory die) into a single package. With the
increased component density in such packaging, there may be
increased power density for which higher efficiency heat transfer
is useful. Also, there may be different thermal demands or
requirements for the dice included the multi-die package 800 that
may be better achieved with the heat transfer devices described
herein.
[0087] The multi-die package 800 includes a plurality of dice,
including die 810, die 820a, die 820b, die 830a, and die 830b, that
are mechanically and electrically coupled to a package substrate
805. In the example illustrated in FIG. 8A, the dice are coupled to
a top of package substrate 805, but in other examples one or more
dice may be located within the package substrate 805. The package
substrate 805 also includes interconnection pins (for example, ball
grid array pins), such as pin 806, for coupling the multi-die
package 800 to a printed circuit board (PCB) or another electronic
component and conducting electrical power and signals. The package
substrate 805 further includes interconnects (not illustrated in
FIG. 8A) within the package substrate 805 that provide electrical
interconnections between and among the dice 810, 820a, 820b, 830a,
and 830b, and the interconnection pins. In the example illustrated
in FIG. 8A, the multi-die package 800 includes a first
three-dimensional dice stack 835a that includes die 830a, and a
second three-dimensional dice stack 835b that includes die 830b;
however, in other examples, three-dimensional dice stacks may not
be included. Such three-dimensional dice stacks have been employed
for increasing capacity and density of memory devices, among other
devices. In the example illustrated in FIG. 8A, a top surface of
each of dice 810, 820a, and 820b, and three-dimensional dice stacks
835a and 835b are exposed, which improves thermal conductivity for
heat transfer. However, in other examples the dice and/or
three-dimensional dice stacks may be encapsulated, such as within a
resin or ceramic material, and a heat transfer device used that
provides separate thermal domains for dice included in the
multi-die package 800. Dice and/or dice stacks included in the
multi-die package may be referred to as individual electronic
components.
[0088] FIG. 8B illustrates an example cross-section (labeled "8B"
in FIG. 8A) of the multi-die package 800 illustrated in FIG. 8A and
an example heat transfer device 801 thermally coupled to, and
providing separate thermal domains for, a first die 810 and a
second die 820a included in the multi-die package 800. Heat
transfer device 801 may include the various features, properties,
characteristics, materials, and/or arrangements as described above
with reference to FIGS. 1A-4, 5B, and 6A-7B. In the example
illustrated in FIG. 8B, the first die 810 is disposed laterally (in
the X direction) from the second die 820a, with the first and
second dice 810 and 820a spaced apart by a lateral distance 829a
between a first inner edge 812 for the first die 810 and a second
inner edge 822a for the second die 820a. Much as with the
previously described heat transfer devices, the heat transfer
device 801 includes a hermetically sealed first chamber 840 (for a
first thermal domain), with a wick 850 therein, that is positioned
adjacent to a hermetically sealed second chamber 845 (for a second
thermal domain), with a wick 855 therein. A shared internal
dividing wall 870 is illustrated, but arrangements such as those
illustrated in FIGS. 6A-7B may also be employed.
[0089] In the example illustrated in FIG. 8B, the first chamber 840
is spaced apart from the second chamber 845 by a lateral distance
871; in this example, lateral distance 871 corresponds to a
thickness of the dividing wall 870. The lateral distance 871
between the first and second chambers 840 and 845 is less than a
lateral distance 829a between the first inner edge 812 for the
first die 810 and the second inner edge 822a for the second die
820a. In this example, the dividing wall 870 and the entire
corresponding lateral distance 871 are laterally positioned between
the lateral positions of the first and second edges 812 and 822a.
The first chamber 840 is disposed above the second die 820a and is
thermally coupled to the second die 820a at a first evaporator
region 860 of the first chamber 840. The second chamber 845 is
disposed above the first die 810 and is thermally coupled to the
first die 810 at a second evaporator region 865 of the second
chamber 845. With this arrangement, first die 810 and second die
820a are in separate thermal domains, which may be tuned and
operated separately as discussed previously. In some examples, die
820b may also be included in the same thermal domain as die 820a.
In some examples, as illustrated in FIG. 8B, the first chamber 840
covers the second die 820a, including extending laterally across
the second die 820a. In some examples, as illustrated in FIG. 8B,
the second chamber 845 covers the first die 810, including
extending laterally across the first die 810. In some examples, as
illustrated in FIG. 8B, the first chamber 840 and/or a bottom wall
of first chamber 840 is not disposed above the first die 810, and
the second chamber 845 and/or a bottom wall of second chamber 845
is not disposed above the second die 822a. Such arrangements ensure
effective thermal coupling of the first and second chambers 840 and
845 to their respective second and first dice 820a and 810, and
also improved thermal decoupling of the first die 810 from the
second die 820a. In some examples, the heat transfer device 801 and
the first and second dice 810 and 820a may all be included in the
multi-die package 800, to better ensure and maintain precise
alignment and thermal coupling between the heat transfer device 801
and the first and second dice 810 and 820a over its lifespan.
[0090] FIG. 8C illustrates an example cross-section (labeled "8C"
in FIG. 8A) of the multi-die package 800 illustrated in FIG. 8A and
an example heat transfer device 802 thermally coupled to, and
providing separate thermal domains for, a die 810 and a
three-dimensional dice stack 835a included in the multi-die package
800. Heat transfer device 802 may include the various features,
properties, characteristics, materials, and/or arrangements as
described above with reference to FIGS. 1A-4, 5B, 6A-7B, and 8B. In
the example illustrated in FIG. 8B, the die 810 is disposed
laterally (in the X direction) from the three-dimensional dice
stack 835a, with a top surface of the die 810 and a top surface of
the three-dimensional dice stack 835a spaced apart by a lateral
distance 839a between a first inner edge 812 for the die 810 and a
second inner edge 837a for the top die 831a of the
three-dimensional dice stack 835a. Heat transfer device 802 is much
like heat transfer device 801, and includes a hermetically sealed
first chamber 842 (for a first thermal domain), with a wick 852
therein, that is positioned laterally adjacent to a second
hermetically sealed chamber 847 (for a second thermal domain), with
a wick 857 therein. A shared internal dividing wall 872 is
illustrated, but arrangements such as those illustrated in FIGS.
6A-7B may also be employed.
[0091] In the example illustrated in FIG. 8C, the first chamber 842
is spaced apart from the second chamber 847 by a lateral distance
873; in this example, lateral distance 873 corresponds to a
thickness of the dividing wall 872. The lateral distance 873
between the first and second chambers 842 and 847 is less than the
lateral distance 839a between the first inner edge 812 for the die
810 and the second inner edge 837a for the three-dimensional dice
stack 835a. In this example, the dividing wall 872 and the entire
corresponding lateral distance 873 are laterally positioned between
the lateral positions of the first and second edges 812 and 837a.
The first chamber 842 is disposed above the top die 831a of the
three-dimensional dice stack 835a and is thermally coupled to the
three-dimensional dice stack 835a at a first evaporator region 862
of the first chamber 842. The second chamber 847 is disposed above
the die 810 and is thermally coupled to the first die 810 at a
second evaporator region 867 of the second chamber 847. With this
arrangement, die 810 and three-dimensional dice stack 835a are in
separate thermal domains, which may be tuned and operated
separately as discussed previously. In some examples,
three-dimensional dice stack 835b may also be included in the same
thermal domain as three-dimensional dice stack 835a. In some
examples, as illustrated in FIG. 8C, the first chamber 842 covers
the three-dimensional dice stack 835a, including extending
laterally across the top die 831a of the three-dimensional dice
stack 835a. In some examples, as illustrated in FIG. 8C, the second
chamber 847 covers the die 810, including extending laterally
across the first die 810. In some examples, as illustrated in FIG.
8C, the first chamber 842 and/or a bottom wall of first chamber 842
is not disposed above the die 810, and the second chamber 847
and/or a bottom wall of second chamber 847 is not disposed above
the three-dimensional dice stack 835a or die 831a. Such
arrangements ensure effective thermal coupling of the first and
second chambers 842 and 847 to their respective three-dimensional
dice stack 835a and die 810, and also improved thermal decoupling
of the three-dimensional dice stack 835a from the die 810. In some
examples, the heat transfer device 802, die 810, and
three-dimensional dice stack 835a may all be included in the
multi-die package 800, to better ensure and maintain precise
alignment and thermal coupling between the heat transfer device 802
and the dice included therein over its lifespan.
[0092] FIG. 9A illustrates an example of a die 910 that may be
thermally coupled to a heat transfer device 901 (not illustrated in
FIG. 9A) to provide separate thermal domains for portions of a
single die 910. For example, die 910 may be, but is not
necessarily, a system on a chip (SoC) that integrates multiple
functions into a single die, such as, but not limited to, one or
more microprocessors, a graphics processing unit (GPU), one or more
coprocessors, a memory controller, memory (such as, but not limited
to, ROM, RAM, and/or nonvolatile memory), radio frequency (RF)
communications (such as cellular data or Wi-Fi), external interface
controllers (for example, for Universal Serial Bus (USB), PCIe,
and/or Ethernet), analog interfaces (such as, but not limited to,
ADCs and/or DACs), voltage and/or power regulation circuits, and/or
various peripheral and circuitry for interconnecting and
controlling such functions. Such SoCs have been increasingly common
for realizing smaller form factor devices (as a single SoC die may
provide the functions otherwise provided using multiple separate
dice and/or packages), adding special purpose functions to
programmable devices, and reducing power consumption.
[0093] Die 910 includes first and second die portions 912 and 914
for which separate thermal domains are provided by the heat
transfer device 901. The first and second die portions 912 and 914
may be referred to as first and second electronic components. In
the example illustrated in FIG. 9A, the first die portion 912 is
disposed laterally (in the Y direction) from the second die portion
914, with the first and second die portions 912 and 914 spaced
apart by a lateral distance 916 between a first inner edge 913 for
the first die portion 912 and a second inner edge 915 for the
second die portion 914. In some implementations, the first and
second die portions 912 and 914 may be disposed immediately
adjacent to each other. Many dice have uneven power densities under
various operating conditions, which can result in die portions that
may benefit from operating with a thermal domain separate from
other portions of the die. In an example in which die 910 is an SoC
in which the first die portion 912 corresponds to a first GPU
function and the second die portion 914 corresponds to a second
microprocessor function, rather than allowing periods of increased
GPU activity, and resulting heat generated by the first die portion
912, to increase the temperature of other portions of die 910 (such
as second die portion 914), a separate thermal domain may reduce
thermal crosstalk between the first and second die portions 912 and
914 and provide a cooling solution tuned to the requirements for
the first die portion 912 and/or the second die portion 914. As
heat is more effectively transferred upward out of the die 910 than
laterally across or through the die 910, the heat transfer device
901 is able to effectively reduce thermal crosstalk between
different portions of a single die. It is noted that the first
and/or second die portions 912 and 914 do not necessarily
correspond to specific functions of the die 910. Although the
example in FIG. 9A illustrates die 910 coupled directly to a PCB
905, in some other examples the die 910 may be mechanically and
electrically coupled to a package substrate much as the first die
810 is coupled to the package substrate 805 illustrated in FIGS.
8A-8C. In the example illustrated in FIG. 9A, a top surface 911 of
the die 910 is exposed, which improves thermal conductivity for
heat transfer when thermally coupled to the heat transfer device
901, as illustrated in FIG. 9B. However, in other examples the die
910 may be encapsulated, such as within a resin or ceramic
material, and a heat transfer device used that provides separate
thermal domains for the first and second die portions 912 and 914
of the single die 910.
[0094] FIG. 9B illustrates an example cross-section (labeled "9B"
in FIG. 9A) of the die 910 illustrated in FIG. 9A and an example
heat transfer device 901 thermally coupled to, and providing
separate thermal domains for, a first die portion 912 and a second
die portion 914 included in the die 910. Heat transfer device 901
may include the various features, properties, characteristics,
materials, and/or arrangements as described above with reference to
FIGS. 1A-4, 5B, 6A-7B, and 8B. Much as with the previously
described heat transfer devices, the heat transfer device 901
includes a hermetically sealed first chamber 920 (for a first
thermal domain), with a wick 930 therein, that is positioned
laterally adjacent to a hermetically sealed second chamber 925 (for
a second thermal domain), with a wick 935 therein. A shared
internal dividing wall 950 is illustrated, but arrangements such as
those illustrated in FIGS. 6A-7B may also be employed. In the
example illustrated in FIG. 9B, the first chamber 920 is spaced
apart from the second chamber 925 by a lateral distance 952; in
this example, lateral distance 952 corresponds to a thickness of
the dividing wall 950. The lateral distance 952 between the first
and second chambers 920 and 925 is less than the lateral distance
916 between the first inner edge 913 for the first die portion 912
and the second inner edge 915 for the second die portion 914. In
this example, the dividing wall 950 and the entire corresponding
lateral distance 952 are laterally positioned between the lateral
positions of the first and second edges 913 and 914. The first
chamber 920 is disposed above the first die portion 912 and is
thermally coupled to the first die portion 912 at a first
evaporator region 940 of the first chamber 920. The second chamber
925 is disposed above the second die portion 914 and is thermally
coupled to the second die portion 914 at a second evaporator region
945 of the second chamber 925. With this arrangement, die portions
912 and 914, although included in the same die 910, are in separate
thermal domains, which may be tuned and operated separately as
discussed previously. In some examples, as illustrated in FIG. 9B,
the first chamber 920 covers the first die portion 912, including
extending laterally across the first die portion 912. In some
examples, as illustrated in FIG. 9B, the second chamber 925 covers
the second die portion 914, including extending laterally across
the second die portion 914. In some examples, as illustrated in
FIG. 9B, the first chamber 920 and/or a bottom wall of first
chamber 920 is not disposed above the second die portion 914, and
the second chamber 925 and/or a bottom wall of second chamber 925
is not disposed above the first die portion 912. Such arrangements
ensure effective thermal coupling of the first and second chambers
920 and 925 to their respective first and second die portions 912
and 914, and also improved thermal decoupling of the first die
portion 912 from the second die portion 914. In some examples, the
heat transfer device 901 and the die 910 may both be included in a
single package, to better ensure and maintain precise alignment and
thermal coupling between the heat transfer device 901 and the die
910 over its lifespan. The techniques described in combination with
FIGS. 9A and 9B may be combined with the techniques described in
combination with FIGS. 8A-8C to provide multiple thermal domains
for a single die included in a multi-die package.
[0095] FIG. 10 illustrates an example of a portable electronic
device 1000 incorporating a heat transfer device as discussed in
previous examples. The portable electronic device 1000 and various
portions including electronic components, may each be referred to
as an "electronic assembly." Portable electronic device 1000
includes a heat transfer device (not illustrated in FIG. 10) which
may include the various features, properties, characteristics,
materials, and/or arrangements as described above with reference to
FIGS. 1A-4, 5B, 6A-7B, 8B, 8C, and 9B. In the example illustrated
in FIG. 10, the portable electronic device 1000 includes a head
mounted display (HMD) and associated electronic components. Such
HMDs may be used for virtual reality (VR), augmented reality (AR),
and mixed reality (MR) applications. The particular example
illustrated in FIG. 10 is a self-contained AR device including
electronic components used for sensing, computing, signal
processing, graphics processing, and display functions, among
others. The illustrated portable electronic device 1000 is similar
in many respects to the HoloLens by Microsoft of Redmond, Wash.,
US. Examples of similar devices are described in U.S. Patent
Application Publication Nos. 2016/0212888 (published on Jul. 21,
2016) and 2017/0099749 (published on Apr. 6, 2017), which are each
incorporated herein by reference in their entireties. Portable
electronic device 1000 includes a headband 1010 for placing the
portable electronic device 1000 on a user's head. Portable
electronic device 1000 includes an electronic processing section,
which includes heat generating electronic components for which heat
needs to be removed. Portable electronic device 1000 includes a
left see-through display device 1030a for a user's left eye and a
right see-through display device 1030b for a user's right eye, for
which a protective shield 1035 is provided. Portable electronic
device 1000 uses a first heat rejection device 1040a and a second
heat rejection device 1040b for rejecting heat. First heat
rejection device 1040a includes a thermal tunnel 1050a which
improves heat rejection, and second heat rejection device 1040b
includes a similar thermal tunnel.
[0096] FIG. 11A illustrates an example heat transfer device 1100
arranged to provide multiple thermal domains for the portable
electronic device 1000 illustrated in FIG. 10. Heat transfer device
1100 may include the various features, properties, characteristics,
materials, and/or arrangements as described above with reference to
FIGS. 1A-4, 5B, 6A-7B, 8B, 8C, and 9B. Heat transfer device 1100
defines three thermal domains: a first thermal domain including
subchambers 1110, 1112, and 1114 that together provide a
hermetically sealed first vapor chamber, a second thermal domain
including subchambers 1120 and 1122 that together provide a
hermetically sealed second vapor chamber, and a third thermal
domain including subchambers 1130 and 1132 that together provide a
hermetically sealed third vapor chamber. There is a first dividing
wall 1142 between subchambers 1112 and 1142 which, in some
examples, may be arranged much as illustrated in FIGS. 6A-7B. There
is a second dividing wall 1144 between subchambers 1114 and 1144
which, in some examples, may be arranged much as illustrated in
FIGS. 6A-7B. There is a third dividing wall 1146 between
subchambers 1120 and 1130 which, in some examples, may be arranged
much as illustrated in FIGS. 6A-7B. In some examples, the
subchamber 1110 may be divided into two subchambers with an
additional dividing wall, thereby providing two thermal domains in
place of the first thermal domain. Heat transfer device 1100
includes a plurality of apertures, including apertures 1150a and
1150b, for attaching heat transfer device 1100 to portable
electronic device 1000.
[0097] FIG. 11B illustrates an example in which the heat transfer
device 1100 illustrated in FIG. 11A is included in the portable
electronic device 1000 illustrated in FIG. 10. Portable electronic
device 1000 includes a first processing section 1160 that includes
a first electronic component 1162 and a second electronic component
1164. The first electronic component 1162 is thermally coupled to
an evaporator region of the subchamber 1120 of the second thermal
domain. The second electronic component is thermally coupled to an
evaporator region of the subchamber 1130 of the third thermal
domain. Portable electronic device 1000 includes a second
processing section 1170 including a plurality of electronic
components mounted on one or more PCBs and thermally coupled to
respective evaporator regions of the subchamber 1110 of the first
thermal domain. Portable electronic device 1000 includes a sensor
unit 1175 which may be thermally coupled to the heat transfer
device 1100, such as to the first thermal domain. A plurality of
fasteners, including hex screws 1155a and 1155b inserted in
respective apertures 1150a and 1150b, are inserted through the
apertures in the heat transfer device 1100 to mechanically secure
heat transfer device 1100 on portable electronic device 1000.
[0098] In FIG. 11B, portable electronic device 1000 also includes a
first thermal conduit 1180a that is arranged to conduct heat to
heat rejection device 1040a, and a second thermal conduit 1180b
that is arranged to conduct heat to heat rejection device 1040b.
The first thermal conduit 1180a includes an end 1182a with a first
portion thermally coupled to a condenser region of subchamber 1114
of the first thermal domain, and a second portion thermally coupled
to a condenser region of subchamber 1132 of the third thermal
domain. The subchamber 1132 has a larger area of contact with
thermal conduit 1180a, allowing it to reject heat at a higher rate
than subchamber 1114. Likewise, the second thermal conduit 1180b
includes an end 1182b with a first portion thermally coupled to a
condenser region of subchamber 1112 of the first thermal domain,
and a second portion thermally coupled to a condenser region of
subchamber 1142 of the second thermal domain. Examples of thermal
conduit in HMDs are described in U.S. Patent Application
Publication Nos. 2016/0212879 (published on Jul. 21, 2016) and
2016/0381832 (published on Dec. 29, 2016), which is incorporated
herein by reference in its entirety. The subchamber 1142 has a
larger area of contact with thermal conduit 1180b, allowing it to
reject heat at a higher rate than subchamber 1112. With the
illustrated use of the heat rejection device 1100, portable
electronic device 1000 can exploit the various benefits described
above for multiple thermal domains.
[0099] While various embodiments have been described, the
description is intended to be exemplary, rather than limiting, and
it is understood that many more embodiments and implementations are
possible that are within the scope of the embodiments. Although
many possible combinations of features are shown in the
accompanying figures and discussed in this detailed description,
many other combinations of the disclosed features are possible. Any
feature of any embodiment may be used in combination with or
substituted for any other feature or element in any other
embodiment unless specifically restricted. Therefore, it will be
understood that any of the features shown and/or discussed in the
present disclosure may be implemented together in any suitable
combination. Accordingly, the embodiments are not to be restricted
except in light of the attached claims and their equivalents. Also,
various modifications and changes may be made within the scope of
the attached claims.
[0100] While the foregoing has described what are considered to be
the best mode and/or other examples, it is understood that various
modifications may be made therein and that the subject matter
disclosed herein may be implemented in various forms and examples,
and that the teachings may be applied in numerous applications,
only some of which have been described herein. It is intended by
the following claims to claim any and all applications,
modifications and variations that fall within the true scope of the
present teachings.
[0101] Unless otherwise stated, all measurements, values, ratings,
positions, magnitudes, sizes, and other specifications that are set
forth in this specification, including in the claims that follow,
are approximate, not exact. They are intended to have a reasonable
range that is consistent with the functions to which they relate
and with what is customary in the art to which they pertain.
[0102] The scope of protection is limited solely by the claims that
now follow. That scope is intended and should be interpreted to be
as broad as is consistent with the ordinary meaning of the language
that is used in the claims when interpreted in light of this
specification and the prosecution history that follows and to
encompass all structural and functional equivalents.
Notwithstanding, none of the claims are intended to embrace subject
matter that fails to satisfy the requirement of Sections 101, 102,
or 103 of the Patent Act, nor should they be interpreted in such a
way. Any unintended embracement of such subject matter is hereby
disclaimed.
[0103] Except as stated immediately above, nothing that has been
stated or illustrated is intended or should be interpreted to cause
a dedication of any component, step, feature, object, benefit,
advantage, or equivalent to the public, regardless of whether it is
or is not recited in the claims.
[0104] It will be understood that the terms and expressions used
herein have the ordinary meaning as is accorded to such terms and
expressions with respect to their corresponding respective areas of
inquiry and study except where specific meanings have otherwise
been set forth herein. Relational terms such as first and second
and the like may be used solely to distinguish one entity or action
from another without necessarily requiring or implying any actual
such relationship or order between such entities or actions. The
terms "comprises," "comprising," or any other variation thereof,
are intended to cover a non-exclusive inclusion, such that a
process, method, article, or apparatus that comprises a list of
elements does not include only those elements but may include other
elements not expressly listed or inherent to such process, method,
article, or apparatus. An element proceeded by "a" or "an" does
not, without further constraints, preclude the existence of
additional identical elements in the process, method, article, or
apparatus that comprises the element.
[0105] The Abstract of the Disclosure is provided to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in various examples for the purpose
of streamlining the disclosure. This method of disclosure is not to
be interpreted as reflecting an intention that the claims require
more features than are expressly recited in each claim. Rather, as
the following claims reflect, inventive subject matter lies in less
than all features of a single disclosed example. Thus the following
claims are hereby incorporated into the Detailed Description, with
each claim standing on its own as a separately claimed subject
matter.
* * * * *